Applied Petrochemical Research (v.6, #2)
Low-temperature oxidative asphaltenes liquefaction for petrochemicals: fact or fiction? by Natalia Montoya Sánchez; Arno de Klerk (97-106).
Asphaltene is the heavy and heteroatom-rich fraction of petroleum that is rejected during a solvent deasphalting process. In patent literature there are claims that state that this material can be converted into an aromatic petrochemical feedstock by oxidative liquefaction at low temperature. To evaluate the validity of these claims, asphaltenes from an industrial solvent deasphalting process were oxidized with dry and water-saturated air at temperatures in the range 45–100 °C. Infrared spectroscopy of the oxidized product confirmed that oxygen was incorporated as C=O and C–O. Under all experimental conditions studied little oxidative degradation was observed that would lead to the production of a petrochemical feedstock. Nevertheless, some observations of scientific value were made about the low-temperature conversion of asphaltenes. During autoxidation with dry air, the n-pentane-insoluble fraction increased. On the contrary, when oxidation was conducted with water-saturated air, the formation of additional n-pentane-insoluble material was suppressed. Mild heating of asphaltenes under nitrogen atmosphere also caused the n-pentane-insoluble content to increase. Spectroscopic evidence showed that esters are formed during oxidation at ~100 °C. The temperature dependence of this reaction was explained and a possible reaction pathway for cycloalkane to ester conversion was presented. Ester selectivity was determined by the competition between hydrogen abstraction and β-scission of the alkoxy radical.
Keywords: Asphaltenes autoxidation; Wet oxidation; Heating of asphaltenes
Bitumen heavy oil upgrading by cavitation processing: effect on asphaltene separation, rheology, and metal content by Dipti Prakash Mohapatra; Deepak M. Kirpalani (107-115).
Cavitation processing has been proposed as a greener alternative to solvent dilution or heat treatment of bitumen and other heavy oils to reduce viscosity and hence, improve transportability. The effect of acoustic cavitation under different conditions of sonication frequencies (low- to high- frequency range) and power inputs on asphaltene content, rheological changes, and metal content of bitumen was investigated in this study. Ultrasonic treatment resulted in a decrease in asphaltene content in bitumen that lead to lower viscosity and shear stress over a wide range of shear rates. Over the range of sonication frequencies investigated (20 kHz–1.1 MHz), the sonication frequency of 574 kHz with 50 % power input resulted in low asphaltene content and lower viscosity suitable for improved transportability. Further, comparison of different conditions of sonication frequencies and power inputs were carried out to investigate the effect of ultrasound on properties of asphaltene (elemental analysis and metal content). It was observed that the sonication treatment of bitumen under different conditions of frequencies and acoustic power decreased the H/C ratio. These results showed higher content of aromatic hydrogen and lower content of aliphatic hydrogen in bitumen treated under different conditions of sonication frequencies and intensity. Characterization of asphaltene performed using ICP-MS and TXRF, revealed lower metal content (Ni, Fe, and V) in the asphaltene phase of processed (sonicated) bitumen. The lowered metal content can be attributed to the reduced asphaltene formation as a result of sonication treatment of bitumen.
Keywords: Ultrasonic treatment; Bitumen; Asphaltene; Metal content; Rheology
5-Lumps kinetic modeling, simulation and optimization for hydrotreating of atmospheric crude oil residue by Sameer A. Esmaeel; Saba A. Gheni; Aysar T. Jarullah (117-133).
This research aims at developing a discrete kinetic model of the hydrotreating process of a crude oil residue based on experiments. Thus, various experiments were conducted in a continuous flow trickle bed reactor over a temperature range of 653–693 K, liquid hourly space velocity of 0.3–1.0 h−1, and hydrogen pressure of 6.0–10.0 MPas at a constant hydrogen to oil ratio of 1000 L L−1. The reduced crude residue had been assumed to have five lumps: naphtha, kerosene, light gas oil, heavy gas oil and vacuum residue. An optimization technique based on the minimization of the sum of the squared error between the experimental and predicted compositions of the distillate fractions was used to calculate the optimal value of kinetic parameters. The predicted product composition showed good agreement with the experimental data for a wide range of operating conditions with a sum of square errors of less than 5 %.
Keywords: Atmospheric residue; Hydrotreating (HDT); Trickle bed reactor (TBR); Lumping model
Hydrogenolysis of glycerol aqueous solution to glycols over Ni–Co bimetallic catalyst: effect of ceria promoting by Tao Jiang; Danni Kong; Kun Xu; Fahai Cao (135-144).
A series of Ni–Co bimetallic catalysts supported on γ-Al2O3 with different Ni/Co mass ratio were prepared by incipient wetness impregnation method for glycerol hydrogenolysis. The catalyst with a Ni/Co mass ratio of 1:3 (denoted as Ni1Co3) exhibited the highest conversion. The performance was compared with that of catalysts promoted by Ce. Moreover, the addition of Ce showed a remarkable promoting effect on the catalytic performance when the cerium content was 2.5 wt%. The physicochemical properties of the supported Ni–Co catalysts were characterized by N2 physisorption, XRD, H2-TPR, NH3-TPD, XPS and TEM. H2-TPR profiles revealed that the coexistence of Ni and Co components on support changed the respective reduction behavior of Ni or Co alone, showing the synergistic effect between Ni and Co species. Compared with the TPR profiles of Ni1Co3, it was clearly observed that the reduction peak of nickel oxide and/or cobalt oxide shifted down to the lower temperature zone gradually with the addition of Ce. It was most probable that the addition of Ce favored the formation of the strong interaction between metal species and ceria. The TEM images showed that the addition of Ce component could improve the dispersion of Ni–Co species on support and inhibited the agglomeration of metal particles during the reaction process, which might be responsible for the enhanced stability.
Keywords: Glycerol hydrogenolysis; Ni–Co bimetallic catalyst; Ce promoting effect; Glycols
Synthesis and characterization of Cs-exchanged heteropolyacid catalysts functionalized with Sn for carbonolysis of glycerol to glycerol carbonate by Amirineni Srikanth; Balaga Viswanadham; Vanama Pavan Kumar; Nageswara Rao Anipindi; Komandur V. R. Chary (145-153).
Cs exchanged heteropolyacid catalysts functionalized with various Sn contents were prepared by wet impregnation method. These catalysts were characterized by X-ray diffraction, FT-IR, Raman spectroscopy, temperature programmed desorption of ammonia and BET surface area measurements. The catalytic properties of Sn–CsPW catalysts were evaluated for the synthesis of glycerol carbonate and they exhibit an unprecedented activity for the higher glycerol conversion and selectivity towards glycerol carbonate under vacuum conditions. Sn-functionalized Cs exchanged heteropolyacid catalysts (CsPW) play a significant role in the enhancement of acidity, catalytic activity and stability. The glycerol conversion and the selectivity of carbonate formation mainly depend on the Sn content and acidity of the catalysts. Different reaction parameters such as Sn molar ratio, glycerol to urea molar ratio, reaction temperature were investigated and also optimum conditions were established. The catalyst containing molar ratio of 3:1 Sn–CsPW has shown highest conversion and glycerol carbonate selectivity.
Keywords: Glycerol; Urea; Glycerol carbonate; Carbonolysis; Cs2.5H0.5PWO40
Wastewater treatment in petroleum activities: example of “SEWAGE” unit in the BG Tunisia Hannibal plant by Lotfi Ghnainia; Mabrouk Eloussaief; Kamel Zouari; Chedly Abbes (155-162).
This paper provides a detailed analysis of the sewage system procedure, as well as the occurring problems during the operation of the system and the required corrective actions that should be taken. In the Hannibal gas plant, the used water is exploited from a local deep well drilled in the plant. However, before being used in both of gas process and domestic activities, this water is treated in a specified unit called “Metito Unit” to obtain an over-purified water that can meet with the chemical requirements of the oil/gas process and the health and environment standards. After several steps of the process, the polluted wastewater resulting from several activities within the plant is treated in the “Sewage Unit”. This unit decontaminates wastewater from polluting factors, using the “Extended Aeration Method”. We have shown that in spite of the efficient methods used in the sewage system procedure, several problems can occur during the operating of the system such as hydraulic overloading, high SVI, high Fm ratio, which causes high level of organic pollutants (BOD5 = 42 mg/l), chemical pollution (COD = 85 mg/l), high level of pH 8, chloride (1900 mg/l), and iron (8300 mg/l). We suggest that the quality of the treated wastewater should be improved by the addition of other processes such as constructed wetland process, photo-catalytic oxidation technique which is one of the most efficient methods of wastewater treatment, to produce water quality that is very similar to that of the natural waters.Généralement, de très importantes quantités d’eau sont utilisées dans le secteur d’activités pétrolières pour les procédés du raffinage du pétrole et/ou du gaz ainsi que pour les usages domestiques dans la raffinerie. Les eaux usées qui résultent après les dernières étapes du traitement du pétrole ou du gaz seront rejetées dans la nature après avoir subir un traitement d’épuration pour être compatible avec les normes standard de préservation de l’environnement. Dans ce contexte, nous nous proposons d’étudier l’exemple de l’unité de traitement des eaux usées (sewage unit) dans la raffinerie Hannibal de traitement du gaz naturel de la compagnie BG Tunisia. Dans le chantier Hannibal, situé à 23 km au sud de Sfax, les eaux utilisées sont explorées d’un puits local creusé dans le chantier lui même, ces eaux sont d’abord traitées dans une station d’épuration appelée Metito unit, et ce avant d’être utilisées dans les différentes unités du chantier et les différentes activités domestiques. Après cet usage, les eaux résiduelles sont polluées et sont pour ce fait traitées dans une unité spécifique appelée Sewage Unit dans laquelle les eaux usées passent par des opérations physiques, chimiques et biologiques permettant leur décontamination autant que possible des facteurs polluants. La technologie appliquée dans l’unité de traitement des eaux usées “sewage unit” est basée sur la méthode dite “méthode d’aération poussée”. Cette méthode consiste en quatre opérations principales à savoir: le criblage ou dépistage, l’aération, la stabilisation et la chloration. Dans le présent travail, nous venons de montrer que malgré la haute performance de l’unité de traitement des eaux et l’efficacité des équipements utilisés, des problèmes peuvent survenir dans le procédé d’épuration et seront à l’origine de la modification de la qualité des eaux usées qui seront loin des normes standards de préservation d’environnement, d’où la nécessité d’envisager d’autres solutions beaucoup plus efficaces pour la résolutions de tels problèmes.
Keywords: Wastewater; Management; Sewage system; Extended aeration method; Settling; Chlorination; Screening; Eaux usées; Traitement; Sewage unit; Méthode d’aération poussée; Criblage; Chloration; Stabilisation
Water-treated Rh/γ-Al2O3 catalyst for methane partial oxidation by Xia Xu; Alan M. Lane (163-166).
A water treatment technique, using H2 as a reducing agent in a wet environment, was applied to a conventional Rh/γ-Al2O3 catalyst. Both standard- and water-treated Rh/γ-Al2O3 catalysts were prepared and their catalytic performances were tested in methane partial oxidation reaction. The water-treated Rh/γ-Al2O3 catalyst shows higher CO selectivity and lower CO2 selectivity between 300 and 600 °C, compared with the standard-treated catalyst. The enhancement is attributed to the formation of well-dispersed smaller Rh nanoparticles.
Keywords: Rh/γ-Al2O3 catalyst; Methane partial oxidation; Water treatment