Applied Petrochemical Research (v.7, #2-4)
Technical review on flexible processing middle distillate for achieving maximum profit in China by Zhanquan Zhang; Wei Zhang; Yalin Zhang; Dewei Ji; Haiyan Jin; Gang Wang; Zhihua Zhang (67-77).
Currently, refining business is experiencing a transformation from refining to chemical business, or integration of refining and chemical business due to the slow economic growth, and decreased demand of clean fuels, particularly diesel product. Diesel products are over-supplied based on the consumption data in China. Refineries are pursuing technologies that could reduce diesel output, particularly the inferior light cycle oil (LCO) fraction. Herein, this article mainly describes the industrialized technologies for LCO processing such as LCO upgrading, LCO blending into available plants such as fluid catalytic cracking (FCC), and hydro-refining/treating unit, LCO moderate hydrocracking, and LCO to aromatics and gasoline with the integration of selective hydro-refining and optimized FCC. It is figured out that the LCO moderate hydrocracking can provide more gasoline at the expense of high H2 consumption, while LCO to aromatics and gasoline (LTAG) technology needs more steps for clean fuel production and retrofitting of FCC plant. Based on the analyses of current technologies, it is suggested that implementation of such technologies should consider the configuration of refineries, as well as the benefit of employed technologies instead of realizing the target for decreasing diesel product unilaterally.
Keywords: Middle distillate; Processing; Diesel; Transformation; LCO fraction
Energy efficiency improvement in an ethylene plant propylene refrigeration cycle (C3R) by Delano Mendes de Santana; Anderson Luis Cassinoni de Oliveira; Evelyn Kraneck; Thais Helena A. Bierrenbach de Camargo; Reinaldo Antonio Cardoso (79-83).
A typical refrigeration cycle in an ethylene plant utilizes propene as fluid. When C3R is still in the warm zone, there is some process heat exchangers that leave it sub-cooled. This creates the opportunity for operational improvement in these systems which will result in less parasite steam formation on cycle expansion zone. The objective is analyze this energy efficiency improvement opportunity, showing the financial and energy earnings. The methodology applied to achieve this improvement in the energy efficiency of this cycle is based on: mass and energy balance calculation, design data comparison, and analysis of differences between the actual values and the design reference. An action plan was developed with necessary implementation steps and earnings calculations. The annual amount realized was around one million dollars in 2015. In terms of natural resources, this work is bringing an average reduction of 1.07 kg/s of steam, representing an amount of approximately 2.12 MW. This gain is about 2% of the turbine consumption. This framework can be applied at any Ethylene plant that has the similar equipments.
Keywords: Energy efficiency; Operation improvement; Propylene refrigeration cycle (C3R); Ethylene plant
Ultrasonic condition boosts up the rate of phase transfer catalyzed polymerization of acrylonitrile in two-phase system by Elumalai Marimuthu; Vajjiravel Murugesan (85-96).
An ultrasound condition associated with phase-transfer catalyst (PTC) has great diverse applications in synthesis of various organic and polymeric materials because of its fast reaction and high yield in short period of time. Phase transfer catalyst (cetyltrimethylammonium bromide as PTC) extracts the reactive radical anion from aqueous phase and transfer to organic phase whilst ultrasound condition enhances the radical formation; consequently, acrylonitrile was polymerized in ethyl acetate/water two-phase system at 60 ± 1 °C under ultrasound (25 kHz/300 W) and silent condition. The rate of polymerization (R p) was doubled under ultrasound compare to silent condition. The various experimental parameters such as monomer, initiator, catalyst and temperature, solvent polarity on the rate of polymerization was studied in both conditions. The activation energy (E a) and other thermodynamic parameters were calculated. The E a value of ultrasound condition supports the enhancement of rate of polymerization. On the basis of observed results, a suitable kinetic model, mechanism and effect of ultrasound in the rate of polymerization were discussed. The obtained polymer was analyzed by TG/DTA and FT-IR. The viscosity average molecular weight of the polymer was found to be 6.8526 × 104 g mol−1.
Keywords: Kinetics; Ultrasound condition; Phase-transfer catalyst; Rate of polymerization; Two-phase system
Improved performance of hierarchical porous Mo/H-IM-5 catalyst in methane non-oxidative aromatization by Heng Liu; Qiubin Kan (97-105).
Two novel hierarchical porous IM-5-S and IM-5-M materials were synthesized using mesoporous silica SBA-15 and MCM-48 as the silica sources, and for comparison conventional IM-5-C zeolite was also synthesized with the same synthesis composition. IM-5-S and IM-5-M samples exhibited larger crystal sizes and different textural properties than the conventional IM-5-C zeolite. Moreover, Mo-modified catalysts, Mo-IM-5-S, Mo-IM-5-M, and Mo-IM-5-C, were prepared for the non-oxidative aromatization of methane. The physical properties and acidities of the samples were characterized by XRD, SEM, TEM, BET, and NH3-TPD. Compared with Mo-IM-5-C, the Mo-IM-5-S and Mo-IM-5-M catalysts showed higher yields of aromatics and better stabilities. The preferable catalytic behaviors of Mo-modified mesoporous IM-5 catalysts may be attributed to the generation of secondary mesoporous systems within the zeolite crystals, which may influence the location and state of the active Mo species, simultaneously lead to easier access to the active sites for reactants and be favorable for the diffusion of products formed in the microporous channels during the methane aromatization reaction.
Keywords: Mesoporous; IM-5; Zeolite; Molybdenum; Methane aromatization
Oxidative dehydrogenation of ethane with carbon dioxide over Cr2O3/SBA-15 catalysts: the influence of sulfate modification of the support by P. Thirumala Bai; S. Srinath; K. Upendar; T. V. Sagar; N. Lingaiah; K. S. Rama Rao; P. S. Sai Prasad (107-118).
Unmodified and sulfate-modified SBA-15-supported Cr2O3 catalysts were prepared by impregnation method. The physico-chemical properties of the supports and catalysts were determined by nitrogen adsorption/desorption, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), laser-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (UV-DRS), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR) techniques. Oxidative dehydrogenation of ethane to ethylene (ODE) with CO2 as oxidant was carried out on these catalysts in a fixed-bed reactor at temperatures in the range of 600–700 °C and at atmospheric pressure. The changes in structural and textural properties because of sulfate modification were identified. Sulfate modification affected the nature of interaction of CrO x species with the SBA-15 support. During the evaluation, it was observed that sulfate modification enhances ethane conversion and ethylene selectivity of the catalyst. Better dispersion of CrO x and the increase in Cr6+/Cr3+ ratio seem to be the reasons for the higher performance of the sulfate-modified catalysts compared to that of the unmodified catalyst.
Keywords: Oxidative dehydrogenation of ethane; Carbon dioxide; Chromium oxide; Ethane; Ethylene; Sulfated SBA-15
Density, viscosity, surface tension, and excess properties of DSO and gas condensate mixtures by Ahmad Khorami; Seyed Ali Jafari; Mohamad Mohamadi-Baghmolaei; Reza Azin; Shahriar Osfouri (119-129).
Disulfide oil (DSO) mostly burned or stored is known as a low-grade byproduct in gas refining industries. This material is highly perilous to environment. A common way to reduce the environmental impact of DSO is blending in a specific ratio with gas condensate stream in gas refinery. This would improve DSO quality and consequently strengthen its unique application. In this work, density, viscosity and surface tension of DSO and gas condensate mixtures were measured and modeled. Viscosity and density of DSO, gas condensate, and their mixtures were measured in temperature range of 283.15–318.15 K. In addition, surface tension was measured at 298.15 K at different volumetric fractions of DSO–gas condensate mixture. Excess molar volume (V E), viscosity deviation (∆μ), deviation of excess Gibbs free energy (∆G E), and excess surface tension (σ E) were determined based on measured properties. Results showed a positive and negative trend for excess molar volume and excess surface tension, respectively. While fluctuation was observed in viscosity deviation and deviation of excess Gibbs free energy and results showed positive and negative values in different mole fraction. In addition, Redlich–Kister equation is proposed to predict excess properties of DSO and gas condensate mixtures.
Keywords: DSO; Gas condensate; Excess property; Viscosity; Gibbs free energy; Surface tension
Kinetic modeling and study of H-ZSM-5 coated silicon carbide ceramic foam in toluene methylation to produce xylene by Debarpita Ghosal; Uttam Maity; Sonali Sengupta; Jayanta Kumar Basu (131-142).
This work deals with the toluene alkylation reaction with methanol catalyzed by commercial H-ZSM-5 coated over SiC foam. The main product is xylene which is a well-known building block of many petrochemicals. The foam has been purchased and H-ZSM-5 was coated on it by dip-coating method. The coated foam was used as a catalyst block to study the reaction of toluene with methanol. The effect of variation of different reaction parameters such as reaction temperature, mole ratio of reactants, W/F ratio, partial pressure, feed rate, number of ceramic block coated with catalyst was investigated. Effect of regeneration of the catalyst has also been studied. In addition, comparison of conversion with pellet and coated one was also studied to confirm the usefulness of ceramic foam as catalyst support to get the best conversion to xylene production.
Keywords: Ceramic foam; H-ZSM-5; Xylene; Toluene; Methanol; Langmuir–Hinshelwood model
Simulation and optimization of different pressure thermally coupled distillation for separating a close-boiling mixture of n-butanol and iso-butanol by Lixin Liu; Liuliu Zhu; Lanyi Sun; Minyan Zhu; Guili Liu (143-150).
Substantial quantities of energy are required in conventional distillation columns applied in high-purity separation of close-boiling mixtures. To achieve energy saving of distillation, a novel different pressure thermally coupled distillation (DPTCD) was proposed for separating the close-boiling mixture of n-butanol and iso-butanol. Both this intensified energy integration technique and two other processes, namely conventional distillation (CD) and vapor recompression column (VRC), were simulated in process simulator Aspen Plus. The optimization was carried out to determine the optimal values of design and operating variables on the basis of minimizing energy consumption. Subsequently, the energy saving and economic efficiency of the DPTCD scheme were evaluated through the comparison with the other two processes. The results showed that, compared to the CD and VRC processes, the energy consumption of DPTCD process was decreased by 65.21 and 15.79%, respectively, and the total annual cost (TAC) of DPTCD process can be reduced by 33.75 and 10.46%. It demonstrated that DPTCD scheme was the most promising alternative to reduce the total energy consumption and TAC with high purity (99.1 wt%) n-butanol and iso-butanol products among these separation processes.
Keywords: n-butanol; Iso-butanol different pressure thermally coupled distillation energy saving total annual cost
Enterprise-wide optimization in a petrochemical plant: a MILP approach to energy efficiency improvement by Delano Mendes de Santana; Sérgio Ricardo Lourenço; Douglas Alves Cassiano (151-160).
Public policy, dollar rate, market prices, contracts values and equipment efficiency influence the costs of the energy sources at an ethylene plant. The aim of this research is to identify energy efficiency opportunities at the energy management resources in a petrochemical industry. It was proved that using MILP makes it possible to achieve energy efficiency gains. MILP proved to be effective, accurate and robust. It confirmed the importance of modeling and simulation with quick response and its implementation in a higher possible rate, since the potential gains running the model once per day were 81% higher than performing it once a month. The optimal resources choice had an average annual potential saving of US$ 556.000/year.
Keywords: Energy efficiency; Decision-making; Modeling simulation; MILP; Ethylene plant
Effect of Fe impregnation sequence on ethanol synthesis from syngas over Mn and Fe promoted Rh/γ-Al2O3 by Fang Li; Weixing Qian (161-167).
Fe promoted Rh–Mn/Al2O3 catalysts with different Fe impregnation sequences were used for ethanol formation from syngas. The effect of Fe impregnation sequence on the structure and performance of the catalysts was investigated by means of N2 adsorption, CO adsorption, H2-TPR, H2-TPD, CO-TPD, XPS and DRIFTS. The results showed that the RhMnFe/Al2O3 catalyst prepared by co-impregnation method showed higher ethanol selectivity than those prepared by sequential impregnation methods. Characterization results indicated that the RhMnFe/Al2O3 catalyst exhibited moderate CO hydrogenation and dissociation ability, stronger CO insertion ability and synergistic effect, which was responsible for its higher ethanol selectivity.
Keywords: Ethanol synthesis; Fe impregnation sequence; Rh-based catalyst
Grafting dual polar monomers onto hydroperoxidized polypropylene with the assistant of supercritical carbon dioxide by Dengfei Wang; Jian Wang (169-179).
A hydroperoxidized polypropylene (HPP) was obtained by oxidizing PP porous particle in solid phase, followed by impregnating dual polar monomers of pentaerythritol triacrylate (PETA) and styrene (St) into the HPP with the aid of supercritical carbon dioxide (scCO2). Then, HPP was used as polymerization initiators and PETA/St were grafted onto microporous PP backbone in water medium. Effects of hydroperoxidation temperature, time, oxidant dosage and PP diameter on hydroperoxides concentration and G p and G e were illustrated systematically. Besides, effects of scCO2 swell time, pressure, monomers concentration and ratio, grafting reaction time and temperature on G p and G e were also examined. Results showed that G p can be easily controlled by changing process conditions; G e was observed to be greater than 90% in most of the cases. Gel content of grafted samples was also determined. The structures and thermal properties of grafted copolymers were characterized through FTIR, SEM, TGA and DSC.
Keywords: Hydroperoxidized polypropylene; Supercritical carbon dioxide; Pentaerythritol triacrylate; Styrene; Grafting
Synthesis and crystal structure of N,N-dimethylformamide solvate of thiocyanuric acid by Rashid Altamimi; Abdulaziz A. Bagabas; Hazem A. Ghabbour; Obaid Alruqi; Mohammed Alnogedan (181-186).
Considerable attention has been paid recently to crystal engineering; which involves the design and preparation of new crystalline molecular solids with desired properties [1–4]. Crystalline materials with specific properties find applications in petrochemical industry for separation and purification. Moreover, crystal engineering provides products designed for manufacturing catalysts and high-valued chemicals for specific purposes. Recently, crystalline materials find application in pharmaceutical, food and microelectronic industries . The main two strategies that are used for crystal engineering are based on hydrogen bonding and coordination bonding . Since the hydrogen bonding is usually stronger and more directional than the other methods, more new crystal materials have been prepared based on this method. We are here able to design crystalline materials based on hydrogen bonding and study their solid state structures. N, N-dimethylformamide (DMF)-solvate of thiocyanuric acid (TCUA) and dimethyl sulfoxide (DMSO)-solvate of thiocyanuric acid (TCUA) were successfully prepared at room temperature in the presence of aqueous solution of sodium nitrate (NaNO3). To the best of our knowledge, this study presents the easy, modest, and rapid method to prepare co-crystal formation based on thiocyanuric acid (TCUA) and solvent-containing hydrogen bonding functionality. In this paper, we present the most effective method to synthesize the co-crystals of (TCUA), and as evidence, the crystal structure of (TCUA) in DMF is fully studied and presented in this paper. The N,N-dimethylformamide (DMF)-solvate of thiocyanuric acid (TCUA) was successfully prepared at room temperature, and was characterized spectroscopically by nuclear magnetic resonance (NMR) and single-crystal X-ray diffraction (SXRD). The asymmetric unit of the title compound contains one molecule of thiocyanuric acid (TCUA) features an almost planar six-membered ring having exocyclic C-S thione double bonds and one molecule of N,N-dimethylformamide (DMF). It was crystallized in the monoclinic, P21/c with unit cell parameters of a = 9.6255 (4) Å, b = 12.6864 (5) Å, c = 9.1367 (4) Å, β = 90.095 (2)°, V = 1115.71 (8) Å3, Z = 4. The structure is composed of 1-D TCUA ribbons formed via N–H–S hydrogen bonds. The ribbons are separated by DMF molecules, which are bridged to the ribbons by N–H–O hydrogen bonds. The ribbons and their DMF molecules form 2-D sheets which are in turn π-stacked to build up a layered, 3-D structure. The proton and carbon-13 NMR studies confirmed the formation of such solvate between DMF and TCUA.