Upgrading of middle distillate fractions of a syncrude from Athabasca oil sands

Current processes for upgrading bitumen from Athabasca oil sands produce synthetic crudes which are high in aromatics and deficient in hydrogen. As a consequence, middle distillate fractions derived from these syncrudes produce diesel fuels of low cetane number and jet fuels which are hydrogen deficient. Results obtained from bench-scale hydrotreating experiments indicate that quality fuels may be produced from Athabasca syncrudes. Middle distillate fractions from this source were subjected to high-severity hydroprocessing in a continuous-flow reactor unit using conventional hydrotreating catalysts which were pre-sulphided by a mixture of $\text{H}{}_2\text{H}{}_2\text{S}$. Aromatic hydrogenation at high temperatures and pressures was affected by the approach to thermodynamic equilibrium, however, at lower temperatures, in some cases virtually 100% saturation was achieved and treated fractions were found to meet cetane number and jet fuel smoke point requirements. Data treatment in the present study includes a model for the hydrogenation kinetics and correlations between aromatic carbon and fuel combustion properties.     

Investigation on drying of middle distillate by Pervaporation

The drying of middle distillate (MD), from which diesel fuel is made, by Pervaporation (PV) was experimentally investigated in a laboratory plant applying organic membranes. The work was conducted in cooperation with a refinery in which MD is catalytically desulphurized by hydrogenation. The H2S formed is separated by steam stripping. The resulting water content in the MD is removed by decanting and subsequent vacuum drying. The objective was to investigate whether drying to low ppm water content is technically possible by the process of PV and to find out about the feasibility of replacing the vacuum drying by PV to save energy. The drying to low ppm water content was accomplished successfully. Permeate total and pure water fluxes are reported. Economic estimations compared vacuum drying costs taken from an existing plant with a design for a full scale multi-module PV plant. The run time of a plant for the point, at which energy savings make up for higher investment costs is estimated.     

Response to comments on upgrading of middle distillate fractions of a syncrude from Athabasca oil sands

In response to an interpretation made by Moore and Akgerman of data taken from a recent publication, previously unexplainable phenomena are accounted for, based on new experimental results. These relate to a thermodynamic equilibrium reaction involving saturation of aromatic hydrocarbons in synthetic crude middle distillates.     

Chemical composition of the distillate fractions of coal tar from OAO Altai-Koks

The chemical composition of the distillate fractions with boiling points of to 180, 180–230, and 230–280°C separated from undehydrated coal tar from OAO Altai-Koks was studied by gas chromatography-mass spectrometry. A list of identified aromatic compounds (including N-, O-, and S-containing compounds) and their alkyl derivatives is given. It was found that, upon the complete processing of tar with the recirculation of residual raw materials at the stage of coking and its hydrogenation refining in the presence of suspended Mo- and Ni-containing catalysts and a hydrogen donor (tetralin), the yields of chemical products were the following (wt %): coke, 50–55; absorption oil, 9–12; benzene, naphthalene, tetralin, dimethylnaphthalenes, and other hydrocarbons, 25–30; BTX fraction 4–5; and C₁-C₄ and CO₂, 10–12.     

中油型加氢裂化催化剂的研制及其性能评价

以改性Y分子筛、Beta分子筛和无定形硅酸铝为酸性组分,W-Ni为活性金属组分,采用等体积浸渍法制备中油型加氢裂化催化剂。采用XRD、SEM-EDS、BET和XRF等对催化剂进行表征,在200 mL加氢评价装置上评价加氢裂化性能和活性稳定性。结果表明,催化剂具有较强的加氢裂化活性、良好的活性稳定性和中油选择性。在反应压力14.5 MPa、氢油体积比1 500∶1、体积空速1.5 h^-1和原料油＞370 ℃馏分转化率70%条件下,中油选择性为78.5%,C₅⁺液体收率为98.40%。（65~140） ℃重石脑油芳潜45.06%,（140~370） ℃柴油十六烷值61.2,＞370 ℃尾油BMCI值7.6,分别可作为优质的重整装置进料、柴油调和组分及乙烯裂解原料。     

Syntheses and investigations of copolymers for improving the flow of middle distillate oils

The results of a review of the patent literature on polymeric flow improvers for distillate fuels showed that a diverse range of polymeric compositions is effective. Ethylene-containing compositions predominate and of these ethylene-vinyl acetate (EVA) copolymers are the most common. Ethylene-vinyl acetate copolymers were synthesised using a high pressure autoclave. The effectiveness of the copolymers varied greatly with the chemical composition of the copolymer. The techniques described in the literature for the determination of the composition of EVA copolymers are summarised and reviewed. A new technique using proton nuclear magnetic resonance was developed. A statistical analysis of the results is presented.     

Characterization of high-boiling petroleum distillate fractions by proton and 13C nuclear magnetic resonance spectrometry

High-boiling (535–675 °C) distillate fractions of Wilmington (Calif. USA) and Gach Saran (Iran) crude oils were separated into saturate, monoaromatic, diaromatic and polyaromatic-polar fractions by passage through a silica-gel—alumina dual packed chromatography column. These fractions were further separated on the basis of molecular volume by gel-permeation chromatography (g.p.c.). Select g.p.c. fractions were then analyzed by ¹H and ¹³C n.m.r. spectroscopy. The fraction of aromatic carbons (Ar-C) of the total carbon content of a given series of g.p.c. fractions, obtained directly from the ¹³C n.m.r. spectra, showed a significant range of values (e.g. 13.2% to 29.2%) within each series. Furthermore, the values of %Ar-C within a series of g.p.c. fractions showed a maximum in each case. No such maximum was observed in the ¹H n.m.r. spectra for the fraction of aromatic proton (%Ar-H) content compared to the total proton content of any of the g.p.c. fraction series. Signals observed in the ¹³C n.m.r. spectra confirmed the presence of aliphatic chains attached to aromatic structures in the monoaromatic, diaromatic and polyaromatic-polar g.p.c. series of each distillate fraction. Well-defined signals, not attributable to straight-chain aliphatic material, were also observed in the ¹³C n.m.r. spectra. Comparison of the chemical shifts of these ¹³C n.m.r. signals with those spectra of model compounds obtained experimentally, and with appropriate systems in the literature, strongly suggested the presence of saturated terpenoid-like structures as well as the presence of methyl groups in sterically hindered positions on an aromatic ring system. Gated decoupling techniques and the use of a relaxation agent were used to overcome the deleterious effects of slow relaxation times and Nuclear Overhauser Enhancement (NOE) on the analytical quality of the ¹³C n.m.r. spectra.     

影响蜡油多产中间馏分油加氢裂化催化剂因素的规律研究

以工业上常用的改性Y型分子筛(HY、USY、NNY)为主要酸性组分,Ni-W为活性金属组分,采用等体积浸渍法分别制备了分子筛类型、分子筛含量、磷助剂加入量、Hβ分子筛加入量、金属负载量、金属原子配比等不同的催化剂。以山东利华益集团减二线蜡油为原料油在100 mL固定床加氢装置上对各系列催化剂进行评价。结果表明,载体中分子筛(NNY与Hβ质量比为2∶1)总含量为30%～40%,P改性剂加入量为1. 5%,金属总负载质量分数为30%,原子质量比[m(Ni)∶m(Ni+W)]为0. 4时制备的催化剂具有较高的转化率、液体收率、中油选择性和脱硫脱氮率。     

Production of middle distillate in a dual-bed reactor from synthesis gas through wax cracking: Effect of acid property of Pd-loaded solid acid catalysts on the wax conversion and middle distillate selectivity

Although alumina-supported gold nanoparticles are poor catalysts for the oxidation of carbon monoxide, they have turned out to be promising candidates for the preferential oxidation of CO in hydrogen-rich streams (PrOx), as hydrogen apparently enhances the CO oxidation rate. The mechanism of this promotion effect is unclear. In this study, we carry out kinetic measurements on the PrOx reaction catalyzed by a 0.9% Au/Al₂O₃ catalyst, which is prepared by direct anionic exchange. We show that the apparent activation energy of the oxidation of CO is lower than that of the oxidation of H₂, whatever the hydrogen content in the feed. On the other hand, the hydrogen partial reaction order is higher in the oxidation of H₂ than in the oxidation of CO. Thus, the CO oxidation rate is significantly increased at low temperature by the introduction of only a small amount of hydrogen in the reactant mixture. At higher temperatures, the selectivity to CO₂ decreases due to competition with the oxidation of H₂. Higher hydrogen concentrations cause the competition between CO and H₂ oxidations to start at lower temperatures. It is proposed that hydrogen reacts with oxygen to yield highly oxidizing intermediates that selectively react with CO as long as the energetic barrier to produce water from these intermediates is not crossed.     

Effect of catalytic combustion of hydrogen on the dehydrogenation processes in a membrane reactor. I. Mathematical model of the process

Mathematical modeling of a catalytic membrane reactor was performed for thermodynamically coupled processes using as an example the endothermic dehydrogenation of propane and the exothermic combustion (oxidation) of hydrogen. Benefits of using the membrane reactor to increase the yield of target products by shifting equilibrium was demonstrated theoretically. The effect of hydrogen combustion on the main characteristics of the endothermic dehydrogenation process was studied. The hydrogen combustion reaction makes it possible to further increase the conversion of propane and compensate for the energy consumption in the endothermic dehydrogenation process.     

Determination of liquid and solid phase composition in partially frozen middle distillate fuels

A liquid-solid separator apparatus was constructed and a method developed for the separation and characterization (g.c.-m.s.) of the crystals and liquid from partially frozen middle distillate fuels. The filtrate data were straightforward, but the precipitate presented problems in interpretation since the waxy crystals entrapped significant amounts of liquid. Since it was not possible to remove all of the entrapped liquid from the precipitate, an indirect method was derived to determine the composition of the liquid-free crystalline material. This required that the fraction of entrapped liquid in the precipitate be known, which could be determined from the g.c. data. Tracer materials in the original fuel were selected which did not crystallize out at the temperatures under study and therefore showed no appreciable concentration change with temperature. These tracer materials were used to estimate the fraction of entrapped liquid in the precipitate. Results obtained by this technique were tested and confirmed by h.p.l.c.     

Conversion of propene into gasoline and middle distillate using alkalised ZSM-5 zeolite catalysts

Propene can be readily converted into aromatic gasoline using catalysts containing H-ZSM-5 as the active component. Catalysts which contain small amounts of alkali give gasoline rich in alkenes. The olefinic gasoline so produced can easily be converted into a wider boiling range material using strong acid catalysts such as aluminium chloride.     

On the link between intrinsic catalytic reactions kinetics and the development of catalytic processes: Catalytic dehydrogenation of ethylbenzene to styrene

A procedure linking kinetic modeling of catalytic reactions to reactor modeling for different configurations is developed and applied to the catalytic dehydrogenation of ethylbenzene to styrene. The procedure is applied to four configurations, namely fixed bed with/without hydrogen selective membranes and bubbling fluidized beds with/without selective membranes. The kinetic data for the industrial catalyst are extracted from industrial fixed bed data using a rigorous heterogeneous model. The kinetic data for the three in-house prepared catalysts are obtained from the laboratory scale experiments using pseudo-homogeneous models.     

Thermally induced redistribution and degradation of bisphenol-A polycarbonate fractions in open and closed systems

Thermally induced chain-scission and redistribution reactions in as-polymerized and fractionated bisphenol-A polycarbonate (PC) materials made by melt-transesterification and interfacial polymerization were studied at temperatures between 200 and 300 °C in open systems, where volatile reaction products are continuously removed, and in closed systems, where these products are retained. Under the applied conditions, PC made via interfacial polymerization shows no measurable susceptibility towards redistribution. This is the result of an extremely low concentration of hydroxyl end-groups. Upon similar thermal treatment, PC made by melt-transesterification undergoes fast redistribution which leads to post-condensation in open systems and strong changes of molecular weight distributions (MWDs) for fractions in all cases. Redistribution effects were visualized through changes in the MWD of mixed fractions. The initial stages of redistribution were simulated using a Monte Carlo method based on a random sampling technique. From comparison between experimental and simulation results, it can be concluded that approximately half a percent of all carbonate linkages is involved in a redistribution reaction per minute at 250 °C for the studied samples.     

Low-temperature properties of triglyceride-based diesel fuels: Transesterified methyl esters and petroleum middle distillate/ester blends

This work examines low-temperature properties of triglyceride-based alternate fuels for direct-injection compression-ignition engines. Methyl esters from transesterified soybean oil were studied as neat fuels and in blends with petroleum middle distillates (No. 1 or No. 2 diesel fuel). Admixed methyl esters composed of 5–30 vol% tallowate methyl esters in soyate methyl esters were also examined. Pour points, cloud points, and kinematic viscosities were measured; viscosities at cooler temperatures were studied to evaluate effects of sustained exposure. Low-temperature filterability studies were conducted in accordance with two standard methodologies. The North American standard was the low-temperature flow test (LTFT), and its European equivalent was the cold-filter plugging point (CFPP). With respect to cold-flow properties, blending methyl esters with middle distillates is limited to relatively low ester contents before the properties become preclusive. Under most conditions, cold-flow properties were not greatly affected by admixing the methyl esters with up to 30 vol% tallowate (before blending). Least squares analysis showed that both LTFT and CFPP of formulations containing at least 10 vol% methyl esters are linear functions of cloud point. In addition, statistical analysis of the LTFT data showed a strong 1:1 correlation between LTFT and CP. This result may prove crucial in efforts to improve low-temperature flow properties of alternate diesel fuels that contain methyl esters derived from triglycerides.     

Intensification of solid-phase reactions by the iodine-transport method

The article represents the possibilities of the iodine-transport method as a technique for intensifying the chemical reaction between solid-phase reagents. The prospects are shown for a decrease in the temperature and an increase in the rates of reactions like the synthesis of compounds from elements and the reduction of oxides using the iodide transport.     

Reactive separation of isobutene from C4 crack fractions by catalytic distillation processes

Reactive distillation is a hybrid process where chemical reaction and distillative separation are performed in a single equipment. Even though reactive distillation could increase the selectivity of the desired product by the selective reaction this is not always true as shown in this work. A study on the MTBE reaction system using two coupled reactive distillation columns to separate a C4 crack mixture is carried out, where methanol acts as reactive entrainer and MTBE is the intermediate product. In the first column, isobutene and methanol react to form MTBE hence separating the inert C4 component, while in the second column MTBE splits back to methanol and isobutene. Methanol is recycled back to the MTBE formation column and isobutene is obtained as a product. This coupled process with direct recycle of methanol is possible only if no side reactions occur. When the side reactions are taken into account, byproducts such as diisobutene, dimethyl ether and water will be produced so that higher purity methanol can not be obtained at the bottom of the splitting column. The outlet of the splitting column must be firstly separated rather than being recycled directly to the formation column. Moreover, an attempt has been made to show how the selectivity of the desired product isobutene can be critically influenced by the operating parameters such as the reflux ratio. If the reflux ratio increases, a high quantity of diisobutene and dimethyl ether will be obtained which seriously affects the selectivity of isobutene. The influence of operating parameters is investigated by using a continuation method, which shows that bifurcation behavior can appear in both MTBE formation and decomposition process.     

Performance enhancement of thermally coupling of methanol synthesis,DME synthesis and cyclohexane dehydrogenation processes: Employment of water and hydrogen perm-selective membranes via different recycle streams

In this research, effect of water and hydrogen perm-selective membranes via different recycle cases in a thermally double-coupled two-membrane reactor (TDCTMR) has been investigated. Methanol and direct dimethyl ether (DME) synthesis from natural gas as exothermic reactions have been thermally coupled with cyclohexane dehydrogenation as an endothermic reaction. Hydroxy sodalite (H-SOD) and Pd/Ag membranes have been employed for removing water from methanol side and injection of hydrogen to DME side respectively. Three different recycle stream cases have been studied for the performance enhancement of TDCTMR. In the first case, the outlet stream from DME reactor is recycled to itself. Also, in the second case, the outlet stream from methanol side is recycled to DME side and finally, the third case is that the mixture of methanol and DME outlet streams are recycled to DME side. The results of these three cases are compared with thermally double coupled reactor (TDCR). Results show that hydrogen production in cyclohexane side of TDCTMR increases 8.32%, 22.89% and 23.88% for cases 1, 2 and 3 in comparison to TDCR respectively. Also, DME and methanol production enhances 38.38% and 13.3% for case 3 (best case) in comparison to TDCR respectively.