Fuel Processing Technology (v.144, #C)
Editorial Board (IFC).
Low-temperature CO2 reforming of methane on Zr-promoted Ni/SiO2 catalyst by Lu Yao; Jia Shi; Hualong Xu; Wei Shen; Changwei Hu (1-7).
Ni–Zr/SiO2 catalyst was prepared using the impregnation method and was employed for the dry reforming of methane. The Ni species ensured a superior dispersion of the Zr species, promoting the formation of low temperature active center for the target reaction, while the introduction of promoter Zr changed the nature of the active center. At high temperature, the Ea values corresponding to CH4 and CO2 on Ni–Zr/SiO2 catalyst were much lower than those on Ni/SiO2 catalyst. In addition to facilitate the activation of the C–H bond in CH4, the Zr promoter on Ni–Zr/SiO2 catalyst also facilitated the formation of COads and Oads species at low temperatures, and accelerated the formation–decomposition of intermediate formates. These factors including the synergetic effect of Ni and Zr species led to the enhancement of the activation of both CH4 and CO2 at low temperatures, with 2.0% initial conversion of both CH4 and CO2 (at 1 h) achieved at 400 °C.
Keywords: Methane; Carbon dioxide; Zr; Low temperature; Catalytic reforming;
Underground coal thermal treatment as a potential low-carbon energy source by Kerry E. Kelly; Ding Wang; Michal Hradisky; Geoffrey D. Silcox; Philip J. Smith; Eric G. Eddings; David W. Pershing (8-19).
We evaluate a novel energy strategy, underground coal thermal treatment (UCTT); it involves slowly pyrolyzing coal in-situ, transforming it to a synthetic gas stream containing hydrogen and low molecular-weight hydrocarbons, liquid fuel and char. This evaluation assesses the life-cycle energy and greenhouse gas (GHG) impacts of UCTT for all process stages. It is based on experimental results at two scales, a simple heat-transfer model and literature results. The results show that UCTT can produce a high-quality liquid product and a gas mixture. UCTT's GHG emissions are in the range of those reported for in situ processing of oil shale. Net energy returns (NERs) of 0.48–4.7 are in the range reported oil sands (2.8) and oil shale (0.48–2.6). Product yield at low temperatures, heater temperature, the number of heaters and the moisture content of the coal are key factors in determining the feasibility of the UCTT process.
Keywords: Coal pyrolysis; Carbon capture; In situ coal; Greenhouse gas emissions; Net energy return;
The suspending role of H2O and CO on catalytic hydrotreatment of gas-oil; myth or reality? by Stella Bezergianni; Vasiliki Dagonikou; Stella Sklari (20-26).
During co-hydroprocessing of petroleum fractions with liquid biomass, carbon monoxide (CO), carbon dioxide (CO2) and water (H2O) constitute some of the main by-products which take place due to the oxygen content of biomass. This study focuses on determining the H2O and CO effect on HDT reactions, as there is a certain controversy associated with their role. H2O and CO are artificially added during gas-oil catalytic hydrotreatment to investigate their influence in the potential biomass (i.e. lipids, bio-oil, tallow oil) catalytic co-hydroprocessing with fossil-based fractions for the production of hybrid fuels. Based on the experimental results, it is clearly inferred that the H2O role is neutral on heteroatoms' removal. On the contrary, CO has a suspending role not due to the resulting hydrogen partial pressure reduction, but rather to the inhibition of the catalyst active sites.Display Omitted
Keywords: Co-hydroprocessing; Methanation; WGS; Water; Gas-oil; Carbon monoxide;
The effect of feedstock composition and taxonomy on the products distribution from pyrolysis of nine herbaceous plants by Adéla Hlavsová; Agnieszka Corsaro; Helena Raclavská; Silvie Vallová; Dagmar Juchelková (27-36).
The effect of feedstock composition and taxonomy on the products distribution from pyrolysis of nine herbaceous plants was evaluated. Specifically, eight members of the Poaceae family and one member of the Fabaceae family were pyrolyzed in a fixed bed reactor to a final temperature of 700 °C. All samples resulted in a medium-energy CO2-rich gas and a phenol-rich liquid. The type of lignin rather than the overall lignin content was found to influence the phenols yield. All samples produced char with a suitable C/N ratio; eight plants produced char with high polarity; and only one sample (i.e., mountain brome) resulted in char with a sufficient aromaticity to be applied to soil. Low carbonization was associated with a high content of inorganic elements that were most likely deposited on the char's surface and blocked vaporization. The product distributions were dependent on (i) chemical and biochemical composition of feedstock, (ii) secondary reactions of liquid and char, and (iii) the samples' taxonomy. Red clover from the Fabaceae family was found to be the most distinct, followed by mountain brome from the Triticodae group (Poaceae family), and the remaining members of the Poodae group (Poaceae family). The least divergence was found between the hybrid samples.
Keywords: Pyrolysis; Grassland biomass; Feedstock composition; Taxonomy; Product distribution;
Continuous production of biodiesel from soybean flakes by extraction coupling with transesterification under supercritical conditions by Qin-Qin Xu; Qi Li; Jian-Zhong Yin; Dan Guo; Bao-Quan Qiao (37-41).
A continuous process of supercritical extraction coupling with supercritical methanol transesterification was put forward to prepare biodiesel directly from full-fat soybean flakes. This method is meaningful to the industrialized production of biodiesel. It can lower the high cost of the refined vegetable oil as feedstock. Furthermore, it gives a possibility that a mobile biodiesel processor could be easily moved to various locations where raw materials are available and produce biodiesel in situ. The experimental results indicated that a residence time of more than 2.5 h was required to obtain a stable fatty acid methyl ester yield. The maximum biodiesel yield of 86% was obtained at 350 °C, 20 MPa and 3 h, with the molar ratio of methanol-to-oil of about 42:1. In addition, based on the investigation of the process optimization, oil extraction was found to be the crucial step for the coupling process and other promising routes were proposed to improve both the production efficiency and the capacity.Display Omitted
Keywords: Biodiesel; Supercritical extraction; Transesterification; Soybean flakes; Continuous coupling process;
Computational modelling of the condensation of fast pyrolysis vapours in a quenching column. Part B: Phase change dynamics and column size effects by V.S. Kiran Kumar Palla; K. Papadikis; S. Gu (42-55).
The aim of the present work is to provide detailed information on the phase change dynamics of a discrete representation of the pyrolysis vapours in a direct contact heat exchanger (disc and donut quenching column). Eleven compounds were chosen to represent the most common chemical groups found in bio-oil (i.e. acids, aldehydes/ketones, pyrolytic lignin and water). The pyrolytic lignin group is represented through mono-phenolic compounds (i.e. phenol, coniferyl alcohol, guaiacol) whereas the effect of sugar and lignin derived oligomers is neglected. The work aims to identify how different numbers of disc and donut pairs (stages) 3, 5 and 9, affect the condensation performance of the column. The saturation vapour pressures of the individual compounds were calculated based on corresponding states correlations. It is shown that heavy compounds, such as guaiacol, phenol and coniferyl alcohol condense rapidly even with a low number of stages, whereas an increased number of stages is needed to completely capture the heavier acidic (butyric acid) fractions. In all cases, the majority of the acidic fraction (acetic acid and propionic acid) and water were only partially condensed, whereas formic acid and the aldehyde fraction (propanal and pentanal) were not condensed at any stage of the process.
Keywords: Condensation; Liquid collection system; Quenching column; Species transport; Fast pyrolysis; Phase change;
Catalytic pyrolysis of central German lignite in a semi-continuous rotary kiln — Performance of pulverized one-way ZSM-5 catalyst and ZSM-5-coated beads by J. Appelt; W. Heschel; B. Meyer (56-63).
Central German lignites with high numbers of aliphatic and bituminous molecular structures are potential feedstocks for light hydrocarbons as intermediates for the chemical industry. This study pursues a new approach to the direct conversion of lignites by heterogeneous catalysis under pyrolytic conditions and without additional hydrogenation. Promising results were achieved in lab-scale investigations with ZSM-5 catalyst and these results were confirmed at a semi-technical scale rotary kiln. ZSM-5-coated beads were examined as an interesting alternative for reutilization and simple separation from the solid pyrolysis products.Based on parameter studies, the maximum yields of low molecular hydrocarbons occurred at a reaction temperature of 500 °C at a catalyst-to-coal ratio of 0.1 to 0.2 (maf). Comparison between the pulverized one-way ZSM-5 catalyst and ZSM-5-coated beads shows similar results concerning the amounts of pyrolysis products, especially gaseous alkenes like propene. At a certain catalyst-to-coal ratio, comparable results of propene liberation can be found also. The main reaction pathways were identified based on the distribution of the catalytic pyrolysis products, especially of low molecular hydrocarbons.
Keywords: Alkenes; Catalyst; Hydrocarbons; Lignite; Pyrolysis; Zeolite; ZSM-5-coated beads;
Monolithic Zn–Co–Ti based sorbents for hot syngas desulfurization by M. Chomiak; J. Trawczyński; Z. Blok; P. Babiński (64-70).
Charge of monolithic Zn–Co–Ti–O based sorbent was manufactured using natural clay as a binder and tested in model hot syngas desulfurization. Fresh and regenerated sorbent was characterized by XRD, SEM–EDX, XPS, mercury porosimetry, and TPRH2. After four cycles of desulfurization (at 540 °C) and regeneration (540–650 °C), monoliths retained the mechanical integrity and their geometry did not change. Monolithic sorbent captured 5.3 g S/100 g in the first cycle and 13.8 g S/100 g in the last one. Concentration of H2S in the treated gas was lowered from 6000 ppmv to 3 ppmv and the H2S removal efficiency was min. 99.6%. Fresh sorbent contains Zn2Ti3O8 (dominant phase), TiO2 and SiO2, while in the regenerated one always occurs: TiO2 (dominant phase), ZnTiO3, Zn2Ti3O8; SiO2; Zn2SiO4 and ZnAl2O4. Reducibility and the amount of sulfates formed in the used sorbent depend on its position in the bed. After tests, small amounts of free ZnO are present on the surface of the used monoliths. During regeneration the zinc oxide (from Zn–Ti–O mixed oxides) reacts with Al2O3 or SiO2 (clay components), and forms compounds more resistant to deactivation, such as Zn2SiO4 and ZnAl2O4.Display Omitted
Keywords: Hot syngas; Desulfurization; Monolith; Sorbent; Adsorption capacity;
Optimization of microwave dewatering of an Indonesian lignite by Jun Cheng; Fan Zhou; Xin Wang; Jianzhong Liu; Zhihua Wang; Junhu Zhou; Kefa Cen (71-78).
Dewatering of an Indonesian lignite with microwave irradiation was optimized to increase dewatering rate and decrease energy consumption. The energy consumption of the microwave dewatering process was affected by different factors, including addition of microwave absorber, diameter-to-height ratio of lignite pile, particle size and initial moisture content of lignite. The experiment results indicated that adding absorber carbon materials (activated carbon and graphite) and metal oxides (Fe3O4, MnO2, etc.) could increase the dewatering rate and decrease the energy consumption. With increased diameter-to-height ratio of lignite pile, dewatering rate initially increased and then decreased. An optimum value exists for diameter-to-height ratio, which presents maximum dewatering rate but with minimum energy consumption. The enhancement of heat accumulation caused by larger particle size increased the dewatering rate of lignite and decreased energy consumption. The energy consumption decreased with increased lignite weight and initial moisture content. However, the energy consumption initially decreased and then increased with enhanced microwave power. Electric power consumption can be well predicted on the basis of the microwave dewatering kinetics of lignite, which can be well described by the Page model under different conditions.
Keywords: Lignite; Microwave; Dewatering; Heat storage; Energy consumption;
Effect of fiber natures on the formation of “solid bridge” for preparing wood sawdust derived biomass pellet fuel by Lingjun Kong; Ya Xiong; Ting Liu; Yuting Tu; Shuanghong Tian; Lianpeng Sun; Ting Chen (79-84).
Four different types of fibers including rice straw, wheat straw, rubber leaf and nylon were added into wood sawdust to prepare renewable biomass pellets (BPs) at room temperature. The effects of these fiber natures on the physical properties of BPs were investigated by characterizing the elongation, particle density, abrasive resistance and impact resistant index. Experimental results showed that the addition of rice straw and rubber leaf possessed a positive effect on the physical properties of BPs while the addition of wheat straw and nylon had a negative effect. The positive effect of the former can be attributed to the strengthened bonds in the BPs by the intertwining action of a “solid bridge” between these linear hydrophilic fibers and wood sawdust. The negative effect of the latter is due to the repelling role between the hydrophobic fiber and hydrophilic wood sawdust to arrest the formation of their “solid bridge”. Therefore, the added fiber natures highly influenced the formation of a “solid bridge” that determined the physical properties of BPs derived from wood sawdust.
Keywords: Biomass pellet; Sawdust; Fiber nature; Solid bridge;
Lignite temperature distribution during low temperature carbonization process in an industrial width carbonization furnace by Ying Wang; Yongfa Zhang; Jun Liu; Ying Xu; Xingxing Qiao; Tao Li (85-94).
Highly efficient industrial carbonization furnace with a width of 500 mm was established in this study. The characteristics involving temperature increase, variation rules for the thermal conductivity of coal, and the temperature distribution model of the coking chamber in a low temperature carbonization process of lignite performed in the furnace were studied. The results showed that the temperature profile of coking chamber could be divided into three zones: the near, middle, and remote zones. The distinguishing index between near and middle zones was a low-temperature-constant (80–100 °C) stage. ∂ 2 T ∂ t 2 = 0 , ∂ T ∂ t = n were the distinguishing indices between the middle and remote zones. When the lignite was carbonized in a single heat source furnace wall coking chamber, the temperature distribution followed the Chen–Clayton equation. Moreover, the effective thermal conductivity coefficient of coal was affected by the carbonization time and heat transfer distance, which exhibited a unimodal distribution during the carbonization process. Furthermore, the classic one-dimensional unsteady temperature distribution model with heat resource factor and the correction equation of heat temperature thermal conductivity were established. After being corrected, the calculated temperature curve was consistent with the measured temperature curve. The model was confirmed by the residual analysis and the error points were in well agreement with the normal distribution.
Keywords: Lignite; Low temperature carbonization; Heat transfer; Heat conductivity coefficient; Temperature distribution;
Detailed analysis of reacting particles in an entrained-flow gasifier by Andreas Richter; Michele Vascellari; Petr A. Nikrityuk; Christian Hasse (95-108).
For the development of reliable numerical models of entrained flow gasifiers it is crucial to understand and to model correctly the interactions between the hot gas-flow and the coal particles undergoing pyrolysis and char conversion. In this work a laboratory-scale entrained flow coal gasifier was investigated numerically. Based on the detailed analysis of the particle trajectories, the interaction between the flow field and coal particles of different sizes was carefully discussed and analyzed. For small, medium, and large particles, the primary regions for devolatilization, oxidation, and gasification were detected, and the conversion behavior for these particle fractions was quantified in terms of pyrolysis time, residence time, and overall conversion rate. Additional particle-resolved CFD calculations were carried out for representative particles of different sizes in order to study the heat and mass transfer of the isolated particles in detail. Pyrolyzing coal particles and combusting or gasifying char particles were considered at several positions in the reactor, where each location is characterized by different gas compositions and temperatures. For these particles, the flow field, and the species and temperature distributions in the boundary layer are discussed. The particle-resolved calculations demonstrate the impact of the particle Reynolds number and the influence of the mass flow from the particle to the surrounding gas on the overall heat and mass transfer.Display Omitted
Keywords: Coal gasification; Coal combustion; Char conversion; Reactive boundary layer; Pyrolysis; CFD modeling; Particle simulation;
Effect of temperature and relative humidity on NOX removal by dielectric barrier discharge with acetylene by Tao Wang; Baomin Sun (109-114).
NOX removal using dielectric barrier discharge (DBD) plasma was investigated. Results indicated that NO and NOX removal efficiency increased with an increasing temperature. The main reason was that the high temperature increased the dissociation of C2H2, N2 and O2, and the reaction rates involving HO2, CH2 and C2H radicals, promoting NO removal. The addition of H2O at room temperature prevented the discharge in the DBD reactor. At lower energy density, energy transferred from electron to reactant was limited, preventing the dissociation of reactant and leading to a decrease in active species, and then NO removal efficiency decreased. However, NO removal efficiency remained the same at different relative humidity and at higher energy density. Furthermore, the OH radicals generated by the dissociation of H2O contributed to the conversion of NO2 to HNO3, thus improving NOX removal efficiency.
Keywords: Dielectric barrier discharge; Acetylene; Temperature; Relative humidity;
The catalytic properties of K modified PtSn/Al2O3 catalyst for acetic acid hydrogenation to ethanol by Mingchuan Zhou; Haitao Zhang; Hongfang Ma; Weiyong Ying (115-123).
Acetic acid hydrogenation catalysts based on platinum and tin supported alumina were modified by adding potassium with different loading amounts and various impregnation sequences. The modification of K caused red shift of CO adsorbed peak, decreased Pt 4d5/2 binding energy and enhanced carbonyl group adsorption, which can promote the selectivity to ethanol. The block effect of K on acid sites was able to restrain side reaction. Further co-impregnation of Pt and Sn to K-doped support led to the poor dispersion of Pt active sites bringing about the low catalytic activity. While catalysts prepared by impregnating PtSn into K-doped alumina were not proper for acetic acid hydrogenation, but adding 0.5 wt.%K into PtSn catalyst enhanced both selectivity of ethanol from 37% to 64% and conversion of acetic acid from 88% to 93%. Further increasing potassium loading caused little change on catalytic behavior.Display Omitted
Keywords: PtSn catalyst; Potassium promotion; Acetic acid hydrogenation; Ethanol;
Co nanoparticle decorated magnetic core, polymeric ionic liquid shell composites for H2 production by Nurettin Sahiner; Alper O. Yasar (124-131).
Here, firstly iron oxide (Fe3O4) nanoparticles (NPs) were prepared and coated with silica-containing vinyl groups, and then a poly(4-vinyl pyridine) p(4-VP) polymeric shell was synthesized around the silica-coated magnetic particles by micro emulsion polymerization technique (M@p(4-VP)). The magnetic polymeric ionic liquid (PIL) particles: M@p(4-VP)+ C2, M@p(4-VP)+ C4 and M@p(4-VP)+ C6, were then prepared by modifying M@p(4-VP) with 1,2-dibromoethane (DBE), 1,4-dibromobutane (DBB) and 1,6-dibromohexane, respectively. The magnetic PIL particles were used as template for Co metal nanoparticles (MNPs) and, M@p(4-VP)+ C2@Co, M@p(4-VP)+ C4@Co and M@p(4-VP)+ C6@Co were created as magnetic PIL-Co composite catalyst systems. The prepared magnetic PIL-Co composite catalyst systems were used as catalysts in H2 generation from hydrolysis of NaBH4. Various parameters such as the type of PIL template, the concentration of NaOH, the number of metal ion loading reducing processes (Co amounts), the reusability, and the hydrolysis reaction temperature were investigated for their effect on H2 production. Among the prepared PIL-metal composites, M@p(4-VP)+ C4 particles contained 504.6 mg g− 1 Co after 4 metal ion loading-reducing cycles. M@p(4-VP)+ C4@Co particles exhibited excellent catalytic activity in H2 generation from the hydrolysis of NaBH4 and their hydrogen generation rate (HGR) and Turn Over Frequency (TOF) were found as 8.46 ± 0.17 (L H2) (g of Co min)− 1 and 20.79 ± 0.10 and 10.43 ± 0.23 (mol H2) (mol of Co min)− 1, higher than most published data. Also, a very low activation energy (Ea = 22.8 ± 0.8 kJ mol− 1) was calculated for H2 generation for the hydrolysis of NaBH4 catalyzed by M@p(4-VP)+ C4@Co in comparison to similar studies.Display Omitted
Keywords: Microgel/nanogel composites; Magnetic polymeric ionic liquid (PIL); H2 production; Co metal nanoparticles; Hydrolysis of NaBH4;
Evaluation of different strategies to produce biofuels from Nannochloropsis oculata and Chlorella vulgaris by M.P. Caporgno; M. Olkiewicz; A. Fortuny; F. Stüber; A. Fabregat; J. Font; J. Pruvost; O. Lepine; J. Legrand; C. Bengoa (132-138).
The lipid extraction using hexane and methanol:hexane increased the biodegradability of Nannochloropsis oculata by 36% and 24% respectively. Moreover, hexane increased the methane production from raw microalgae, from 253 ± 11 to 313 ± 9 mLCH4/gVS. Methanol:hexane did not affect the methane production, which yielded 254 ± 10 mLCH4/gVS, mainly due to the significant changes in the biomass composition.On the other hand, the lipid extraction failed to increase the biodegradability of Chlorella vulgaris, which resulted around 44% for raw and lipid-extracted microalgae. The methane productions were 219 ± 6, 202 ± 1 and 200 ± 4 mLCH4/gVS from raw and pre-treated microalgae using hexane and methanol:hexane respectively.Regarding the lipid extraction yields, using methanol:hexane the yields were 4.7 and 3.7 times higher for N. oculata and C. vulgaris than using hexane. The biodiesel yields were also higher using methanol:hexane, 2.4 and 1.9 times than using hexane. However, the biodiesel composition was unaffected by the solvent.The substrate to inoculum ratio influenced raw N. oculata digestion. At 1:1 VSSubstrate:VSInoculum, the methane production throughout the first days decreased but not the ultimate methane production. C. vulgaris digestion was unaffected, probably due to the biomass characteristics.Finally, the co-digestion of microalgae and sewage sludge showed no synergy, nor inhibition.Display Omitted
Keywords: Co-digestion; Chlorella vulgaris; Methane; Nannochloropsis oculata; Pre-treatment; Substrate to inoculum ratio (SIR);
Butanol production by Clostridium pasteurianum NRRL B-598 in continuous culture compared to batch and fed-batch systems by J. Lipovsky; P. Patakova; L. Paulova; T. Pokorny; M. Rychtera; K. Melzoch (139-144).
Butanol production by acetone–butanol–ethanol (ABE) fermentation is usually associated with Clostridium acetobutylicum. In this report, ABE fermentation using the little known, oxygen tolerant solventogenic strain, Clostridium pasteurianum NRRL B-598, in packed-bed continuous cultures is described and compared with suspended cells in continuous, batch and fed-batch processes. While the highest butanol and total ABE concentrations (8.3 and 12.3 g/L respectively), were obtained in fed-batch fermentation, the highest solvent yield and productivity (32% and 0.73 g/L/h), were achieved in packed-bed continuous fermentation at a dilution rate of 0.12 1/h. In these processes, the strain showed exceptional stability, as demonstrated not only by low deviations in process parameters in batch and fed-batch experiments but also long-term stability (over 700 h, or more than 35 bioreactor residence times) in continuous fermentations.
Keywords: Butanol; Clostridium pasteurianum; Continuous production; Packed-bed bioreactor; Batch and fed-batch process;
Kinetic modeling and simulation of throated downdraft gasifier by Ozgun Yucel; Mehmet Alaittin Hastaoglu (145-154).
An imbert ‘throated’ gasifier which has hourglass heart and varying axial area and nozzles for injection of gasification agents has been studied. The transport of reacting gas-solid two-phase mixture through the gasifier has been mathematically modeled transiently. Downdraft gasification in such a complex system has so many variables and is quite cumbersome to describe. For the first time throated gasifiers are modeled as realistically as possible. The resulting set of transport, structural, kinetic and auxiliary equations was solved via numerical methods. The modeling work was experimentally validated using a 10 kW gasifier. The actual geometry of the experimental setup was used in the model. The model results were in line with the experimental results. Throated combustion zone causes better distribution of heat and reduces heat loss. With the same core size and solid consumption, stratified gasifier output was 24.5% less than throated one. The model exit had 25.85% CO; 18.25% H2; 7.84% CO2; 2.9% CH4; while the experiment had 35.07–20.77% CO; 18.30–13.66% H2; 13.68–5.95% CO2; 6.7–1.2% CH4; the rest was N2. The model can be applied to different geometries.
Keywords: gasification; imbert; downdraft; modeling; simulation;
Characterisation of ash deposits on a probe at different temperatures during combustion of a Zhundong lignite in a drop tube furnace by Jianbo Li; Mingming Zhu; Zhezi Zhang; Kai Zhang; Guoqing Shen; Dongke Zhang (155-163).
Characteristics of ash deposits formed on an air-cooled stainless steel probe simulating superheater surfaces at different temperatures during combustion of Zhundong lignite in a drop tube furnace were systematically studied. Zhundong lignite in a size fraction of 50–100 μm was combusted in air in the drop tube furnace at 1673 K. Ash deposits formed on both the top tip surface and side surface of the probe maintained at 773 K, 873 K and 973 K, respectively, were collected and characterised using XRD and SEM-EDS for their mineralogy, morphology and chemical composition. The particle sizes and sintering temperatures of the top surface deposits were also determined. At probe temperatures of 773 K and 873 K, the ash deposits on the top surface composed of particles with sizes varying from sub-microns to 100 μm, where fine particles (< 10 μm) had agglomerated and stuck to coarse ash particles (> 10 μm), indicating sintering had occurred. The mineral phases were dominated by anhydrite, lime, nepheline, hematite, quartz, periclase, and mullite. At 973 K, fine particles had melted and incorporated into the coarse particles, leading to increased particle sizes and the formation of a new mineral phase with low melting-point, hauyne (Al6Ca2Na6O32S2Si6), suggesting significant sintering. The ash deposits on the probe side surface, however, were also sintered but composed of fine particles and their aggregates, nominally < 10 μm in size. The mineral phases mainly consisted of anhydrite, lime and periclase, being much less complex than those in the top surface deposits. The fine ash rich in Na, Ca, S, and Mg on the probe due to condensation and thermophoresis is believed to be responsible for the severe ash deposition during combustion of Zhundong lignite.
Keywords: Ash deposition; Drop tube furnace; Mineral matter; Sintering; Zhundong lignite;
Adsorption behaviors of ammonia and hydrogen sulfide on activated carbon prepared from petroleum coke by KOH chemical activation by Takuya Mochizuki; Mitsuhiro Kubota; Hitoki Matsuda; Luis F. D'Elia Camacho (164-169).
For the expansion of utilization of petroleum coke (petcoke), activated carbon (AC) was prepared from petcoke with potassium hydroxide (KOH) chemical activation, and pore structure and surface chemistry of the prepared AC were investigated. Moreover, adsorption behavior of ammonia (NH3) and hydrogen sulfide (H2S) on activated carbon prepared was studied. The specific surface area of AC increased with increasing activation temperature, meanwhile the acidic surface functional groups decreased. Pore structure development was basically promoted with an increase in the KOH/petcoke weight ratio. Ammonia adsorption was found to proceed rapidly even at 303 K, and the amount of NH3 adsorbed was dependent on the surface acidic functionalities, especially for hydroxyl and carboxyl groups on AC surface. On the other hand, hydrogen sulfide adsorption test conducted at room temperature showed that adsorption of H2S proceeded with very slow rate, and the adsorption capacity of H2S was correlated with the pore characteristics of ACs, especially with the micropore surface area.
Keywords: Activated carbon; Petroleum coke; Chemical activation; NH3 adsorption; H2S adsorption;
Continuous production of lactic acid from glycerol in alkaline medium using supported copper catalysts by Arthur B.F. Moreira; Arthur M. Bruno; Mariana M.V.M. Souza; Robinson L. Manfro (170-180).
With increasing demand for biodiesel, large quantity of crude glycerol has been produced both in Brazilian and world market, and this excess glycerol has become a problem that must be solved. Several studies have been performed with the objective to transform glycerol in value-added chemical products. Lactic acid has wide uses in chemical and food industries, and the hydrothermal transformation of glycerol to lactic acid is presented as an alternative to conventional production process. In this study, the production of lactic acid from glycerol under alkaline conditions, using copper (20 wt.% CuO) catalysts supported on Al2O3, ZnO and MgO in continuous flow reaction system was investigated. The catalysts were prepared by impregnation method and characterized by XRF, XRD, N2 adsorption–desorption, TPR, and TPD-CO2 and the dispersion of copper was determined by N2O oxidation. The reaction was carried out at 240 °C, 35 atm, with space velocity (WHSV) of 2 h− 1, 10 vol.% glycerol solution and NaOH/glycerol molar ratio of 0.5, 0.75 and 1.0. All catalysts showed high conversion of glycerol with yield and selectivity to lactic acid in the range of 80 and 90%, respectively, when the reactions are performed with NaOH/glycerol molar ratio of 1.0.Display Omitted
Keywords: Lactic acid; 1,2-propanediol; Glycerol; Copper; Alkaline medium; Continuous production;
Effect of solvent on hydrothermal oxidation depolymerization of lignin for the production of monophenolic compounds by Xinping Ouyang; Tao Ruan; Xueqing Qiu (181-185).
Lignin was hydrothermal oxidation depolymerized by using H2O2 as the oxidant and CuO/Fe2(SO4)3/NaOH as catalysts. The effect of the solvents, including water, methanol, 1,4-dioxane, tetrahydrofuran, ethanol, and their co-solvent, on the depolymerization of lignin were investigated. It is found that the yield of monophenolic compounds reaches 17.92% by using 1:1 (v/v) of methanol/water as the reaction medium. The suitable proportion of methanol to water not only effectively maintains the alkalinity of the reaction medium and the solubility of lignin, but also suppresses the demethoxylation during the process of depolymerization reaction, resulting in an increase of contents of syringyl style monophenolic compounds which prevents the re-polymerization. Consequently, the yield of monophenolic compounds is increased.
Keywords: Lignin; Monophenolic compounds; Oxidation depolymerization; Solvent;
Higher alcohols synthesis via CO hydrogenation on Cu/Zn/Al/Zr catalysts without alkalis and F–T elements by Yong-Jun Liu; Zhi-Jun Zuo; Chao-Bo Liu; Chao Li; Xuan Deng; Wei Huang (186-190).
A series of Cu/Zn/Al/Zr catalysts without alkalis and F–T elements, were prepared with various atomic ratios of Al/Zr by complete liquid-phase technology and tested for higher alcohols synthesis from CO hydrogenation. The results showed that the Cu/Zn/Al catalyst exhibited excellent higher alcohols selectivity, reaching approximately 58.8%. With the increase of Zr/Al atomic ratio, the catalytic activity and stability increased, but methanol became the dominant product in the liquid products over Cu/Zn/Zr catalyst. It was concluded that Al favored the formation of higher alcohols and Zr was beneficial to improve the stability of catalysts. Characterization results showed that the addition of Zr improved the dispersion of Cu and made the catalyst easier to be reduced. It also favored the stability of pore structure and decreased the amount of weak acidic sites. It was also found that the amount of the weak acidic sites played a key role in the higher alcohols formation and the amount of weak acidic sites decrease might lead to the deactivation of catalysts.Display Omitted
Keywords: Higher alcohols; Cu/Zn/Al/Zr catalyst; CO hydrogenation; Complete liquid-phase technology;
Adsorption of hydrogen sulfide as initial step of H2S removal: A DFT study on metal exchanged ZSM-12 clusters by Mehmet Ferdi Fellah (191-196).
The molecular adsorption of hydrogen sulfide has been theoretically studied via DFT on additional framework with cations of metals (Fe, Co, Ni, Cu and Zn) in 14T-channel ZSM-12 zeolite cluster model. The method employed in this study is B3LYP functional with LanL2DZ and 6–31 G(d,p) basis sets. Cu–ZSM-12 cluster has the lowest chemical potential with minimum adsorption energy value with negative ΔG, highest electronegativity and lowest energy gap between HOMO and LUMO with respect to other clusters. It is softer than other clusters because of its lower chemical hardness value. Accordingly, based on these data it can be mentioned that Cu–ZSM-12 is a promising candidate catalyst as for removal of hydrogen sulfide via activation of S–H bond than other metal ZSM-12 zeolites.
Keywords: Hydrogen sulfide; H2S; Adsorption; ZSM-12; MTW; Metals; Density functional theory;
Limits of variations on the structure and the fuel characteristics of sunflower seed shell through torrefaction by E. Bilgic; S. Yaman; H. Haykiri-Acma; S. Kucukbayrak (197-202).
Sunflower seed shell (SSS) that is a woody waste biomass was torrefied at 300 °C which is the upper limit of torrefaction temperature to monitor the most severe variations on chemistry, morphology, functional groups, and the burning characteristics of biomass. Since, this biomass is rich in holocellulose (hemicellulosics + cellulosics) and relatively poor in lignin contents, it offers opportunity to observe the heat-induced variations on a woody biomass. Besides, the effects of torrefaction on SSS were firstly investigated in this paper. Comparison of H/C and O/C ratios before and after torrefaction revealed that the composition of SSS moved from nearly a cellulosic model to a point between lignite and subbituminous coal. It was also concluded that the torrefaction should be implemented at around the upper temperature limit to assure effective removal of volatiles and to improve the biomass. However, the residence time should be optimized to justify the effectiveness of torrefaction and to avoid the loss of carbon.
Keywords: Torrefaction; Temperature; Biomass; Sunflower; Surface functionalities;
Thermal transformation of tobelite from coal at high temperatures and the kinetics and mechanism of dehydroxylation and deamination process by Hui-Rong Zhang; Jin Bai; Ling-Xue Kong; Xin Dai; Zong-Qing Bai; Wen Li (203-211).
Tobelite from coal was processed to remove impurities and submitted to thermal treatments. The thermogravimetric analyzer (TGA) was employed to investigate the thermal behavior of tobelite between 25 and 1500 °C. X-ray diffraction (XRD) and in-situ diffuse reflectance infrared Fourier transformation (DRIFT) spectroscopy were used to examine the structural change of tobelite and the dehydroxylation and deamination process. The results show that the thermal transformation of tobelite can be divided into three stages: − 350 °C (stage I), 350–1000 °C (stage II), and 1000–1500 °C (stage III). The following kinetic triplet in the dehydroxylation and deamination process at stage II were calculated: E α = 199.67 kJ mol− 1, f(α) = (1/3)(1 − α)[− ln (1 − α)]− 2 and A = 6.76 × 1013 min− 1. Meanwhile, the thermodynamic functions (ΔS, ΔH, ΔG) calculated using activated complex theory shows that dehydroxylation and deamination process is endothermic. The proposed mechanism of tobelite decomposition includes multi-step reactions: (1). Condensation of water molecule in the octahedral layer; (2) Transmission of water molecules through the tetrahedral ring; (3) Migration of water and ammonia molecules through the interlayer region and recombination of silica and alumina tetrahedron into metatobelite; (4) Metatobelite transformation into mullite at around 1030 °C. Besides, the deamination and dehydroxylation process proceeds simultaneously, but the former occurs more easily.
Keywords: Tobelite from coal; High temperatures; Kinetics; Mechanism;
Kinetics of fast alkali reactive extraction/in situ transesterification of Chlorella vulgaris that identifies process conditions for a significant enhanced rate and water tolerance by Kamoru A. Salam; Sharon B. Velasquez-Orta; Adam P. Harvey (212-219).
The kinetics of alkali-catalysed reactive extraction (“in situ transesterification”) of Chlorella vulgaris with methanol to produce biodiesel were investigated. Both the experiment and the model showed that a maximum 96% biodiesel yield can be obtained in 10 min before saponification FAME losses become significant. This high FAME yield was achieved despite high levels of free fatty acid (6% lipid) in C. vulgaris. The process shows higher level of water tolerance than a two-step transesterification. At 600:1 methanol to oil molar ratio, the process was not adversely affected by up to 20% moisture in the microalgae. A derived numerical model fitted with experimental data from this study showed that other side reactions including FAME and triglyceride saponification; free fatty acid neutralisation occur alongside the desired biodiesel synthesis in a NaOH-catalysed reactive extraction.
Keywords: Kinetics; Saponification; Chlorella vulgaris; In situ transesterification; Biodiesel; Hydroxide–methoxide equilibrium;
The effects of sugar beet molasses on wheat straw pelleting and pellet quality. A comparative study of pelleting by using a single pellet press and a pilot-scale pellet press by Nevena Mišljenović; Radmilo Čolović; Đuro Vukmirović; Tea Brlek; Carlos Salas Bringas (220-229).
The main aim of this paper is to investigate the effects of molasses on wheat straw pelleting and physical pellet quality. Molasses was added at weight fractions of 1.5% and 3%, while pure straw served as a control. The effects of molasses were examined by producing pellets in a single pellet press (SPP) and in a pilot-scale pellet press (PSPP). The second aim of this study was to compare the results obtained from the SPP and the PSPP, i.e., to understand how the information from the SPP can be used for the prediction of material behavior, process adjustments, and improvement of pellet quality in an upscale pelleting process. The production and pellet quality parameters were compared and information from the two pelleting methods was combined by response surface modeling. Pellet density was the response variable, while pelleting pressure and temperature were the independent variables. Large differences in pellet quality were observed between the two pelleting methods. These differences are discussed from the perspective of technical differences in the pelleting procedures and different fiber orientations in the pellets. The results indicate that pelleting temperature is a key factor for achieving good pellet quality of all the samples. Exceeding the glass transition temperature of lignin leads to significantly better pellet quality and facilitates pelleting. The results showed that molasses strengthens pellets produced at temperatures below the glass transition of lignin. Addition of molasses at higher pelleting temperature did not significantly affect the pellet quality and processability.
Keywords: Straw pellets; Molasses; Single pellet press;
Fluidized bed co-combustion of hydrothermally treated paper sludge with two coals of different rank by Chinnathan Areeprasert; Fabrizio Scala; Antonio Coppola; Massimo Urciuolo; Riccardo Chirone; Prut Chanyavanich; Kunio Yoshikawa (230-238).
Fluidized bed co-combustion of raw paper sludge (Raw-PS) and hydrothermally treated paper sludge (HTT-PS) with either low (Lo-Coal) or high reactivity coal (Hi-Coal) was investigated. The paper sludge was treated in a pilot-scale hydrothermal reactor at 197 °C and 1.9 MPa for 30 min. South African bituminous and Thai subbituminous coals were selected as representative of Lo-Coal and Hi-Coal, respectively. A 110-mm bubbling fluidized bed combustor was used in this study. During the steady combustion tests the nominal temperature was 858 °C, the fluidization velocity was 0.5 m/s, and the excess air was varied as 20%, 40%, and 60%. Both single fuel combustion and co-combustion were tested. Co-combustion tests were conducted by feeding the sludge at mixing ratios of 30% and 50% (mass basis) with coal. The main focus of this study was on NOx emissions and unburned carbon performance. Results showed that at 30% mixing ratio using HTT-PS instead of Raw-PS could reduce NOx emission by 3–6% and 9–17% in the case of Lo-Coal and Hi-Coal, respectively, and the loss of unburned carbon could be decreased by 15–18% and 36–53% for Lo-Coal and Hi-Coal, respectively. The particle size distribution of fly ash of all samples was similar regardless of the excess air variation. On the whole, the hydrothermally treated paper sludge showed better performance for co-combustion with coal and would be a better choice compared to the original raw paper sludge.
Keywords: Fluidized bed; Co-combustion; Paper sludge; Coal; Hydrothermal treatment; NOx;
Petcoke-derived functionalized activated carbon as support in a bifunctional catalyst for tire oil hydroprocessing by Idoia Hita; Roberto Palos; José M. Arandes; Josephine M. Hill; Pedro Castaño (239-247).
The catalytic performance of three NiMo catalysts supported on tailored activated carbon (AC) supports has been studied for the hydroprocessing of tire oil for sulfur removal and conversion of heavier fractions towards lighter naphtha and diesel production. The supports have been obtained through physical activation of petcoke for different times, and in some cases functionalized via acid treatment with HNO3. The hydroprocessing runs have been carried out in a fixed bed reactor working in trickle bed regime at 275–375 °C, 65 bar and a space time of 0.16 h. The catalyst properties have been measured by ICP-AES, N2 adsorption–desorption isotherms, TPR, and tert-butylamine adsorption–desorption (TPD). A preliminary catalyst screening using a synthetic mixture of model compounds of tire oil was used to select the most active catalyst. This catalyst, which contained a support activated for 9 h and functionalized with HNO3, had an HDS conversion of up to 99.9%. In the hydroprocessing of real tire oil, the same NiMo/AC catalyst reached a steady sulfur removal of 96.3% and a heavy gasoil lump removal higher than 11 wt%, with complete olefin hydrogenation and a decreased content of naphthenes and aromatics in the products. The cetane number of the diesel fraction was also enhanced with this catalyst.Display Omitted
Keywords: Tire oil; Hydroprocessing; Hydrodesulfurization; Activated carbon; Naphtha; Diesel;
Structural evaluation of Xiaolongtan lignite by direct characterization and pyrolytic analysis by Yu-Gao Wang; Xian-Yong Wei; Sheng-Kang Wang; Zhan-Ku Li; Peng Li; Fang-Jing Liu; Zhi-Min Zong (248-254).
Organic matter in Xiaolongtan lignite (XL) from Southwest China was analyzed by direct characterization instruments (including solid-state 13C nuclear magnetic resonance spectrometer, X-ray photoelectron spectrometer, and Fourier transform infrared spectrometer) and pyrolytic tools (including thermogravimetric analyzer and Curie-point pyrolyzer-gas chromatograph/mass spectrometer). Organic carbons in XL mainly consist of aliphatic and aromatic carbons. Specifically, methylene dominates in the aliphatic carbons and average carbon number in the methylene chains is ca. 5. Each aromatic cluster contains 2 rings and each aromatic ring has 4 substituents on average. XL is rich in oxygen-functional moieties (OFMs), including Cal–O, Car–O, > C＝O, and –COOH, among which Cal–O and Car–O are predominant and thereby cleaving Cal–O and Car–O bonds facilitates the devolatilization of organic matter in XL. Phenols are the richest components in the volatiles from flash pyrolysis of XL, which may result from the cleavage of Car–O in the organic matter. The pyrolytic analyses imply that selectively cracking these bonds would greatly facilitate converting XL into liquid fuels or fine chemicals.
Keywords: Lignite; Organic matter; Direct characterization; Pyrolytic analysis;
Comparative study on characterization and adsorption properties of activated carbons by phosphoric acid activation from corncob and its acid and alkaline hydrolysis residues by Guang-zhen Zhu; Xian-lun Deng; Min Hou; Kang Sun; Yan-ping Zhang; Ping Li; Fang-min Liang (255-261).
Four activated carbons were prepared from corncob, acid hydrolysis residue, alkaline hydrolysis residue and China fir sawdust respectively with phosphoric acid activation under the same process condition. TG/DTG-DSC analysis revealed that the addition of phosphoric acid decreased the pyrolysis rate while increased the temperature and the yield. The findings showed that the acid and alkaline hydrolysis residue from corncob were both suitable to prepare high performance activated carbon. Moreover, different micropore volume, mesopore volume and mean pore width existed although activated carbons possessed the similar BET surface area and total pore volume. In addition, the liquid phase adsorption and pore properties of activated carbons were contrasted to show that the pore structure varied from one to another though with more or less the same iodine number, methylene blue adsorption and decolorization of caramel. Compared to China fir sawdust, activated carbons from corncob, acid hydrolysis residue and alkaline hydrolysis residue were easily made with a high decolorization of caramel. FTIR results suggested that four activated carbons were found with hydroxyl and phosphorus groups.
Keywords: Activated carbons; Phosphoric acid; Pyrolysis; Liquid phase; Pore structure;
Application of MixAlco® processes for mixed alcohol production from brown algae: Economic, energy, and carbon footprint assessments by Peyman Fasahati; J. Jay Liu (262-273).
Alternative routes of the MixAlco® process, i.e., the ketonization (KR) and esterification (ER) routes, were evaluated for the production of mixed alcohols from brown algae. The alternatives were rigorously simulated using Aspen Plus v.8.6 for 400,000 tons dry brown algae/year. The simulation results were used to develop techno-economic models and to evaluate the alternatives based on their profitability, energy requirements, and greenhouse gas (GHG) emissions. The results showed that the KR is superior, with a net present value (NPV) and present value ratio (PVR) of 61.1 million dollars and 1.57, respectively, over the ER, with a NPV and PVR of − 55.1 million dollars and 0.48, respectively. The total energy costs of the KR and ER were calculated to be 11.6 and 37.2 million dollars/year, respectively, while emitting 109.7 and 307.6 kton CO2 equivalents (CO2-eq)/year GHGs. The economic model was used to perform a sensitivity analysis and calculate a maximum dry seaweed price (MDSP) of 90.0 $/ton for the KR.
Keywords: Biofuel; Brown algae; MixAlco® process; Techno-economic assessment; Carbon footprint;
Upgrading waste tires by chemical activation for the capture of SO2 by Antonio Nieto-Márquez; Evangelina Atanes; Juan Morena; Francisco Fernández-Martínez; José Luis Valverde (274-281).
Waste tires have been upgraded as activated carbon by chemical activation with KOH at different KOH:tire ratios, 0:1, 0.5:1, 1:1 and 4:1, namely AC-0, AC-0.5, AC-1 and AC-4 and characterized in terms of elemental and proximate analyses, nitrogen adsorption/desorption, acid/base and Boehm titrations. An increase in activating agent:tire ratio resulted in an increase in the fixed carbon content, surface area and pore volume, and a decrease in surface basicity and sulfur content. The so-prepared materials were tested in the adsorption of SO2, as an important pollutant from fuel combustion, using a thermogravimetric analyzer. The final adsorption capacity followed the trend AC-0 < AC-0.5 < AC-1 < AC-4, matching that of increasing surface area and pore volume, while adsorption affinity was impacted by both textural and acid/base properties. A kinetic model with statistical validation based on Ritchie's equation successfully matched the transient uptake data, where larger rate constant values were obtained for those carbons presenting higher surface basicity.
Keywords: Waste tire; SO2 adsorption; Activated carbon; Surface basicity;
A comparison of acid treatment in the dewatering of Chinese and Australian lignites by mechanical thermal expression at high temperatures by Qiongqiong He; Hasina Yeasmin; Zhenyong Miao; Keji Wan; Shaomeng Huang; Andrew Hoadley; Ying Qi; Alan Chaffee (282-289).
Mechanical thermal expression (MTE) is an effective and efficient method of dewatering high moisture content lignite. However the high total organic carbon (TOC) of the wastewater requires further chemical treatment, before discharge to the environment. In this work, changes in the characteristics of the solid products and the wastewater are reported, when sulphuric acid is used as part of the MTE process.Two lignites were tested: Loy Yang (LY) from Australia and ShengLi (SL) from China. The characteristics of the solid products and wastewater were analysed for both. The effect of expression temperature (200 °C and 240 °C) on moisture content reduction is evident for LY, but it is only marginal for SL. The final moisture content of the solid product in either case is not impacted by the addition of sulphuric acid, but the mercury porosimetry intrusion analysis showed a greater reduction in pore volume for LY. It is postulated that acid treatment suppresses the solubilization of phenols and carboxylic groups in the case of LY. For SL with a different maceral structure, as the concentration of the solubilized phenolic compounds is much lower when no acid is used, the impact of acid addition is much less significant. It appears that the addition of acid inhibits the dissociation of organics from the lignite macerals and also reduces the rate of dissolution, leading to lower TOC in the wastewater. Thus, the wastewater becomes easier to treat after sulphuric acid addition during MTE. The MTE process also removes dissolved salt and organically-bound minerals which aids in reducing the fouling components in the lignite and possibly the PM10 concentrations in the flue gas following combustion.
Keywords: Lignite; Mechanical thermal expression; Dewatering; Acid treated; Waste water treatment;
Rheological modifiers for petroleum coke–water slurry by David J. Marchand; Alexander Abrams; Brennan R. Heiser; Yongkwang Kim; Juhoe Kim; Seong H. Kim (290-298).
The rheological properties of petroleum coke–water slurries (PWS) were examined and modified using polyvinyl alcohol (PVA), naphthalene sulfonate (NS), and xanthan gum (XG). PVA and NS were both very effective at reducing the slurry viscosity. Adsorption isotherms showed that PVA and NS must be adsorbed to the particle surface to be effective; the viscosity cannot be reduced further once the particle surface is saturated. Decreasing the slurry viscosity also caused very poor stability against settling due to gravity. Adding XG to PVA-treated slurries gave strong shear-thinning behavior, which allowed for excellent stability. PVA and XG are practical and effective for producing PWS with ideal rheological behaviors.Display Omitted
Keywords: Petroleum coke; Petcoke; Slurry fuel; Rheological properties;
Influence of process conditions on the formation of 2–4 ring polycyclic aromatic hydrocarbons from the pyrolysis of polyvinyl chloride by Hui Zhou; Chunfei Wu; Jude A. Onwudili; Aihong Meng; Yanguo Zhang; Paul T. Williams (299-304).
Municipal solid waste (MSW) contains significant amounts of polyvinyl chloride (PVC). The reactivity of PVC may form polycyclic aromatic hydrocarbons (PAHs) during the pyrolysis of MSW, which can become a key challenge during the development of pyrolysis technologies. However, there is very limited work in relation to the influence of pyrolysis process conditions in terms of temperature and heating rate on PAHs formation during pyrolysis of PVC. In this work, the formation of 2–4-ring PAHs from the pyrolysis of PVC at temperatures of 500, 600, 700, 800, or 900 °C and at fast and slow heating rates was investigated under a N2 atmosphere in a fixed bed reactor. With the increase of temperature from 500 to 900 °C, HCl yield decreased from 54.7 to 30.2 wt.%, while the yields of gases and PAHs in the tar increased. Slow pyrolysis generated higher HCl yield, and lower gas and tar yield than fast pyrolysis; the PAH yield obtained from the slow pyrolysis was much lower compared to fast pyrolysis. The results suggest that for fast pyrolysis, the dehydrochlorination of the PVC might be incomplete, resulting in the formation of chlorinated aromatic compounds.
Keywords: Waste; Plastics; Pyrolysis; PAH; PVC;
Sulfur tolerant Co–Mo–K catalysts supported on carbon materials for sour gas shift process — Effect of support modification by Katarzyna Antoniak-Jurak; Paweł Kowalik; Marcin Konkol; Wiesław Próchniak; Robert Bicki; Wioletta Raróg-Pilecka; Piotr Kuśtrowski; Janusz Ryczkowski (305-311).
The effect of steam gasification on the surface composition, surface area, pore size distribution as well as on the morphology of the carbon supports has been investigated. Materials have been characterized by nitrogen physisorption, mercury porosimetry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Model samples of the Co–Mo–K catalysts with the same composition have been prepared on carbon supports differing in the temperature of steam gasification process. Catalytic activity measurements have been carried out in a gradientless reactor in a kinetic regime at low partial pressures of reagents. A relationship between textural parameters of the supports and the catalysts activity has been estimated. The highest activity in the SGS process has been determined for the Co–Mo–K/SRO/40.49 supported catalyst.Display Omitted
Keywords: Sour gas shift; Carbon supported Co–Mo–K catalysts; Carbon black composites; Mesoporous carbon support;
In situ performance of various metal doped catalysts in micro-pyrolysis and continuous fast pyrolysis by Güray Yildiz; Frederik Ronsse; Jop Vercruysse; Jalle Daels; Hilal Ezgi Toraman; Kevin M. van Geem; Guy B. Marin; Ruben van Duren; Wolter Prins (312-322).
Catalytic fast pyrolysis (CFP) of biomass is a promising route for the production of deoxygenated liquids suitable for further conversion to fuels and/or chemicals. In this work, CFP of pine wood in a micro-pyrolysis setup and a continuously operated bench-scale fast pyrolysis unit was performed to investigate the effect of catalyst type and reactor type on the products. In total, eight zeolite catalysts (metal doped acidic, basic, and γ-alumina catalysts and their parent counterparts) were tested. In the bench-scale unit, the distribution of products including liquid organics (i.e. CFP-oil), water, char, coke, and non-condensable gases (NCGs) were measured, as well as the compositions of the CFP-oil and NCGs. CFP gives rise to the production of additional water, coke, and NCGs at the expense of CFP-oil. However, the quality of the obtained CFP-oil was altered significantly depending on the catalyst type. For all catalysts, the acidity of CFP-oils remarkably decreased with an increased deoxygenation. The best performance was obtained with the lower redox-metal containing acidic catalyst and freshly calcined metal doped basic mixed-metal oxide catalysts. Py-GC/MS results obtained with the same catalysts were found to be only partially indicative for the performance of a catalyst in CFP of biomass.
Keywords: Bio-oil; Catalytic fast pyrolysis; Pine wood; Auger reactor; Heterogeneous catalysis; Py-GC/MS;
Influence of surrounding conditions and fuel size on the gasification rate of biomass char in a fluidized bed by Louise Lundberg; Placid A. Tchoffor; David Pallarès; Robert Johansson; Henrik Thunman; Kent Davidsson (323-333).
While the operational conditions of a fluidized bed are known to influence the fuel axial mixing, the effect of the resulting axial location of the fuel particles on the char gasification rate remains unexplored. In this work, a laboratory-scale bubbling fluidized bed was used to investigate how the gasification rate of biomass char was influenced by the fuel axial location (during pyrolysis and char gasification), the pyrolysis atmosphere, the fuel size, and the fuel concentration. When pyrolysis at the bed surface was followed by char gasification inside the dense bed the char gasification rate was up to 2-fold lower than the other combinations of the fuel axial location, which held similar rates. Cooling the char after pyrolysis decreased the char gasification rate in all cases studied. The gasification rate increased when the fuel particle size was decreased, and its dependence on the degree of char conversion was also affected. Thus, the operational conditions of a fluidized bed reactor, through modified fuel axial mixing, can influence the char gasification rate. Furthermore, experimental determination of reactivity data in laboratory-scale systems must account for the axial location of the fuel at the desired end-scale, using similar fuel particle sizes.
Keywords: Fluidized bed; Char gasification; Biomass char; Fuel segregation; Char kinetics;
Bentonite-enhanced biodiesel production by NaOH-catalyzed transesterification of soybean oil with methanol by Lian Wu; Teng-you Wei; Zhang-fa Tong; Yun Zou; Zi-jun Lin; Jian-hua Sun (334-340).
A new reaction system for biodiesel production by the base-catalyzed transesterification process has been developed. Bentonite is used as a water adsorbent in the traditional homogeneous base-catalyzed transesterification reaction system to create a heterogeneous system that improves the reaction efficiency. The influence of bentonite on the NaOH-catalyzed methanolysis of soybean oil and the accompanying reaction mechanisms were investigated. It was found that an appropriate introduction of bentonite can promote the methanolysis. By the rapidly removal of the water from the system, bentonite enhances the transformation of NaOH to the catalytically active methoxide species. Further, the main side reactions are significantly inhibited. The methanolysis of triglycerides took place in the liquid phase rather than in the solid phase. The introduction of bentonite also lowered the soap concentration in crude biodiesel, which was beneficial for the post-treatment to generate refined biodiesel.
Keywords: Biodiesel; Bentonite; Methanolysis; Mechanism; Transesterification;
Criminal removal of fuel markers by distillation by Vincent B. Croud; Clive A. Marchant; Philip Maltas; Lutz Hecht; Roy Douglas (341-347).
Samples of locally sourced UK Diesel fuel spiked with the two organic compounds 2-(butan-2-yl)-1-(decyloxy)-4-(triphenylmethyl)benzene (TPMB) and 1,3-dibromotetrafluorobenzene (BFB) were subjected to laboratory-scale distillations to assess the suitability of TPMB and BFB as effective markers of Diesel fuel. Industrial-scale distillations of these spiked Diesel samples were performed to establish whether TPMB and BFB could be successfully and cost-effectively separated from Diesel on a significantly larger scale. Diesel distillate does not contain any TPMB; newly formulated performance criteria of an ideal, distillation resistant fuel marker clearly reject TPMB as a marker suitable for the tagging of Diesel. In contrast, BFB is retained in all fractions of distilled Diesel and largely satisfies the performance criteria of a distillation resistant fuel marker. BFB consequently functions as a significantly better fuel marker than TPMB for the tagging of Diesel. It is demonstrated that distillation is also a highly effective means of removing current overt dye markers. Conservative estimates suggest that an appropriately equipped laundering facility for the distillative removal of fuel markers or vice versa fuel from marked Diesel offers the potential of generating a vastly lucrative, multi-million pound annual profit.
Keywords: Accutrace™ S10; Diesel; Distillation; Fuel; Fuel laundering; Fuel marker; Fuel marker removal; Fuel taggant; Fuel tracer;