Oxidative Dehydrogenation of Methanol on Chromium Oxide/Montmorillonite K10 Catalysts

Abstract

Methanol conversion was carried out on a mesoporous material—chromia/montmorillonite K10 (MK10)—in a pulse microcatalytic system. Methanol was converted to formaldehyde and ethylene by two different mechanisms. Methanol dehydrogenation increases by increasing reaction temperature (300–400°C) and as chromia loading decrease. On the other hand, the dehydration of methanol occurs at a higher temperature (400–500°C) and as chromia loading increase, 3–18% Cr. Redox and exposed nonredox Cr³⁺ are responsible for formaldehyde formation. There is a relationship between increased C₂H₄ production and the increase of Cr⁶⁺ phase according to the acidity of chromia catalysts 34 and 76 μL tert-Butylamine/g catalyst for 3% Cr and 18% Cr, respectively. Formaldehyde formation is diffusionally controlled at high temperatures (400–500°C) and kinetically controlled at a lower reaction temperature (300–400°C), while methanol dehydration to ethylene is surface reaction controlled at 400–500°C.     

STUDY ON COKING KINETICS OF CHINESE GUDAO VACUUM RESIDUE

Using a molten metal bath as heat source of reaction, the coking kinetics of Gudao vacuum residue in temperature ranges of 400 - 440°C and 460-500°C were studied and kinetic models were developed. The order of reaction, pre-frequency factor and apparent activation energy of thermal-cracking were determined as 1.0, 7.853 × 10¹⁰ min^-1 and 175.3KJ/mol respectively. The results laid a solid foundation for technological computation, reconstruction and design of the tubular furnace using the residuum as its feedstock.     

Oligomerizing Olefins in Light Coke Gasoline to Diesel

We prepare a catalyst for FCC gasoline polymerizing to produce diesel oil, which uses non-noble metal Ni as the main active component; here mesopore γ-Al₂O₃ is used as the carrier. The effects of mass fraction of active components and the condition of preparing were investigated simultaneously. The results show that mass fraction of the main active component is 8%, soakage time is 6 hr, and the roasting temperature is 500°C to roast for 4 hr, which are better conditions for preparing the catalyst. Under the condition of a reaction temperature of 210°C, reaction pressure is 3.0 Mpa, space velocity is 1.0 h^-1, and volumetric percent of diesel is 42.0%, which meet a criterion of -35^# diesel. At the same time we study the stability and regeneration of the catalyst with good results.     

COMPARATIVE REACTION STUDY OF METHYLCYCLOHEXANE AND 3-METHYLHEXANE IN H2 AND N2 ON Pt/Al2O3 CATALYST

The reaction of methylcyclohexane and 3-methylhexane were studied in a pulse microcatalytic reactor using H₂ and N₂ carriers on Pt/Al₂O₃ catalyst at temperatures from 350 to 500°C, contact times (W/F) of 1.25 × 10^-3-3.75 × 10^-3 g min/ml and a total pressure of 4.0 kg/cm². In N₂, there was complete conversion of methylcyclohexane to methane, benzene and toluene while similar products were produced for 3-methylhexane, albeit with diminished conversion level. In H₂, methane was produced from 3-methylhexane conversion while aromatization without demethylation was obtained in addition to some cracking for methylcyclohexane at the low temperature range (350-400°C); a higher temperature range (460-500°C) resulted in complete fragmentation for methylcyclohexane. In H₂-N₂ mixtures, the presence of N₂ of not less than 50% in the carrier gas stream yielded an aromatic catalyst at conditions where only cracking activity was previously evident. The differences in product distribution and/or product types for the two reactants in H₂ and N₂ suggest a different reaction mechanism for both reactants.     

Cyclohexane Dehydrogenation Using an Economical Iron Catalyst: Influence of Alumino-Silicate Structure on the Catalytic Activity

The effect of mixing both local Egyptian hematitic ore and activated aluminosilicate material (bentonite clay) on the dehydrogenation activity of the former was studied.

Three mixtures were prepared in which bentonite percentages were 10, 20, and 40 wt%. Cyclohexane used as a model reactant for the catalytic dehydrogenation reaction carried out in catalytic flow system within reaction temperature ranged from 150 to 500°C in the presence of hydrogen stream (75 mL/min) and at constant space velocity 3.71 h^-1.

The results obtained indicated that in spite of the drop in the selectivity of the local material toward benzene formation by clay addition, a distinct increase in the benzene yield was observed. The maximum conversion attained ∼28.14% at reaction temperature 500°C using a mixture containing 20 wt% activated bentonite.     

ON THE DETERMINATION OF SURFACE FREE ENERGY OF COAL BY MEANS OF THE DERIVATOGRAPH

The calculations of the dispersion γC^d and nondispersion (polar γC^p components of surface free energy of coal on the basis of adsorption measurements of nonpolar (n-heptane) and polar (methanol, propanol, water) liquid vapours a 20°C are presented. Average values ( γC^d = 45.1 mJ/m² and γC^p = 13.2 mJ/m²) are in good agreement with literature data calculated on the basis of separate and independent measurements. The heterogeneous nature of coal surface has been confirmed from derivatographic measurements.     

DEVELOPMENT OF OXIDIZED POLYETHYLENE WAXES

A method of preparation of oxidized polyethylene waxes, which have many applications such as in plastics, rubber, leather, paper, inks and textile, etc. was developed. The experiments of polyethylene waxes oxidization were carried out in a pilot plant. The reactor was a 0.27 m diameter and 3 m high column reactor with a conical distribution plate. The experimental results showed that the optimal conditions for preparation of the Oxidized Polyethylene Waxes were: catalyst KMnO⁴, reaction temperature 141—148°C, reaction time 3-7 h, air velocity 4—8 m/s. The oxidized polyethylene waxes with acid number of above 30 mgKOH/g could be obtained with this method.     

An evaluation of the effect of storage and processing temperatures on the microbiological status of sous vide extended shelf-life products

The microbiological and organoleptic quality of selected sous vide products was monitored over a storage period of up to five weeks at 3°C and 8°C, respectively. Sous vide products stored at the recommended temperature of 3°C showed negligible microbial growth and were found to be organoleptically acceptable throughout the storage period. Total plate counts at the end of the fourth week of storage were in the range <10–7×10³ CFU/g for all 19 products under study. Listeria monocytogenes, Salmonella, Clostridium perfringens, Bacillus cereus and Enterobacteriaceae were not detected in any of the processed samples. At 8°C, under temperature abuse conditions, while some products had acceptable microbial levels of 10²–10⁴ CFU/g after three weeks, others such as chicken chasseur had counts above 10⁶ CFU/g by the second week of storage. Lactic acid bacteria and Pseudomonas species were dominant in the microbial flora of spoilt samples and B. cereus (>3×10⁴ CFU/g) was isolated from spoilt chicken chasseur samples in the fourth week of storage at 8°C. Critical factors affecting sous vide product safety are discussed.     

Etherification Performance of Transition Metals Modified β-Zeolite Catalyst

The etherification experiment for FCC light gasoline on transition metals modified Hβ zeolite was studied in a fixed-bed reactor. The effect of preparation condition of catalyst on the catalyst's activity, stability, and the effect of reaction temperature, methanol/tert-olefin molar ratio, and liquid hour space velocity on the etherification reaction were discussed. The experimental results showed that the different metals modified Hβ zeolite had different etherification performances. And the conversion of tertiary carbon-olefins of the molybdenum modified Hβ zeolite, which was loaded 3%, was higher 6.0% than the Hβ zeolite. The optimal reaction conditions were temperature 70-80°C, liquid hour space velocity 1.0 h^-1 and methanol/tert-olefin molar ratio 1.05. The modified Hβ zeolite catalysts possessed favorable prospect for its higher stability.     

Computer modelling for the control of particulate sterilization under dynamic flow conditions

A finite difference model was used for predicting the centre temperature of particulates during ultra-high temperature processing under continuous flow conditions. This model compared favourably with the analytical solutions. A sensitivity analysis was carried out on the input parameters to the numerical model, which indicated that particulate size and thermal diffusivity were the most critical parameters influencing process lethality and cook value. For example, a spherical particulate (thermal properties defined) of 20 mm diameter required a holding time greater than 5 min at 135°C to achieve a minimum safe cook (F₀ of 3.0 min for Clostridium botulinum), compared to a 10 mm spherical particulate which would have received an F₀ value of 68 min after 5 min processing at 135°C. The centre temperatures predicted using the model were sensitive to changes in the convective surface heat transfer coefficient in the range 100–300 W m⁻² K⁻¹, but became less sensitive as the values increased up to 500 W m⁻² K⁻¹. An initial product temperature change from 20 to 60°C resulted in an 8 min increase in process lethality for a 15 mm spherical particulate processed for 5 min at 135°C. The determination of experimental results in particulates of less than 20 mm (the critical dimension) was found to be significantly affected by conduction errors through the thermocouple wires, and therefore the model presented will be a useful prediction tool in situations of experimental uncertainty.     

Synthesis of Tert-amyl Methyl Ether with Methanol and C5 Hydrocarbons

The reaction system and mechanism of etherification of C5 cut with methanol were analyzed theoretically. Experiments were carried out in a tubular reactor at temperatures of 50°C-80°C in the presence of a strong cation-exchange resin, QRE. In the reaction system, two types of reactions took place: etherification and isomerization. At lower temperature, the reaction rates were controlled by kinetic factors, but at temperature above 60°C, both reactions were affected by thermodynamic equilibrium. The appropriate operating conditions were: T at 60°C-65°C, molar ratio of methanol and isoamylenes 1.0-1.2, and liquid hourly space velocity (LHSV) 1.0-1.5.     

The Role of Nitrogen in Facilitating Methylcyclohexane Aromatization on Pt/Al2O3 and Pt-Re/Al2O3 Catalysts

The kinetics of methylcyclohexane aromatization on commercial Pt/Al₂O₃ and Pt-Re/Al₂O₃ catalysts was investigated in a micro-reactor using N₂ and/or H₂ as carrier gases at temperatures ranging between 300-500°C, W/F values ranging between 0.83-3.75 mg min/mL and at a total pressure of 4.0 kg/cm². On both catalysts in N₂ atmosphere, aromatization accompanied by demethylation was observed with the formation of cracked products, benzene and toluene. However, in H₂ methane was the predominant product of methylcyclohexane reforming on PtA1₂O₃ and Pt-Re/Al₂O₃ at 500°C and 400-500°C respectively, whereas at 350°C, aromatization was predominant on Pt/Al₂O₃ but on Pt-Re/Al₂O₃, aromatization was accompanied by fragmentation to methane. In N₂-H₂ mixtures, demethylation activity was observed to decrease with H₂ content of the mixture on Pt-Re/Al₂O₃. A preliminary test of the kinetic data using Sica's method of pulse kinetic analysis suggests a first order rate in methylcyclohexane with activation energies of 3.21 kcal/gmol in N₂ and 19.70 kcal/gmol in H₂ for the Pt/Al₂O₃ catalyst and 16.66 kcal/gmol in N₂ and 34.94 kcal/gmol in H₂ for the Pt-Re/Al₂O₃ catalyst. However, a more comprehensive kinetic analysis suggested an aromatization mechanism for Pt-Re/Al₂O₃, where adsorbed H₂ was a participant. A different aromatization mechanism for the reaction in N₂ where hydrogen was not needed explained the data on Pt/Al₂O_3. In both cases, the desorption of toluene was determined as the rate determining step.     

LNG汽车技术发展及其推广应用前景

对传统固定流化床反应器进行了必要的改进,将固定流化床反应器拓展应用到甲醇制烯烃反应研究中。通过调整预热温度及更换下行进料管材质,使甲醇在与催化剂接触前的分解几率降到最低。装置平行性及物料平衡考察结果表明,该反应器数据重复性良好,物料平衡可达到97%。采用SAPO-34分子筛催化剂,在固定流化床反应器中分别考察了反应温度和水醇比(质量比)对甲醇制烯烃主要反应产物分布的影响。温度实验结果表明:甲醇转化率接近于100%,反应温度的提高可大大提高乙烯的选择性,C2=～C4=选择性可达到90%以上;同时温度的升高使得催化剂上积炭速率增快;对于以乙烯为主要目的产物的甲醇制烯烃工艺,建议将反应温度选择为500℃,C2=/C3=摩尔比可稳定在1.5左右;若以丙烯为主要目的产物,建议将反应温度选择在450～470℃之间,C2=/C3=摩尔比可稳定在0.9～1.1之间。水醇比实验结果表明:水不但可以延缓催化剂的积炭速率,而且还可以大大增加乙烯的选择性,较大的水醇比可以将C2=/C3=摩尔比提高到2.0以上;无论是期望乙烯为主要目的产物还是丙烯为主要目的产物,太大的水醇比会增加能耗,增大反应器及产物分离器的负荷,所以,建议将水醇比都选择在0.25～0.5之间。     

DEEP DESULPHURISATION OF A DIESEL BLEND IN A PILOT PLANT TRICKLE BED REACTOR

A pilot plant investigation was conducted to study the influence of hydrotreating conditions on conversion and characteristics of diesel blend and to determine the severity of operating conditions required to meet the proposed product specifications for diesel fuel in India. A typical diesel blend derived from various refinery streams with sulphur content of 2·06 wt% was hydrodesulphurised over a commercial NiO-MoO₃/Al₂O₃ catalyst in a pilot plant trickle bed reactor. The experiments were conducted at 300-370°C, 30-50 kg/cm², 2·0 3·0 hr^-1 liquid hourly space velocity and constant H₂/oil ratio of 185 m³/m³. The data showed that the diesel blend could be hydrotreated to meet revised product specifications of 0·25 wt% sulphur, 46 cetane number by increasing the severity of operation. The cetane number and aromatic saturation were limited by thermodynamic equilibrium at temperatures above 360°C. The influence of temperature was found to be more pronounced than that of pressure in the range of operating conditions studied.     

碳四烃芳构化产物的综合利用研究

以大庆石化公司混合碳四为原料,在500 mL碳四芳构化模试装置上进行了碳四烃芳构化产物综合利用的研究。研究结果表明,在反应温度360～400 ℃、反应压力2.0 MPa、氢油体积比50:1、体积空速1.0 h-1的条件下,采用纳米分子筛为基础研制的碳四芳构化催化剂具有较高的活性,产品结构合理,芳构化产物中的C3～C4馏分可以作为乙烯裂解原料的一个补充,C5～C10馏分可以作为高辛烷值汽油调合组分。     

IN-SITU ACTIVATION OF METHANOL SYNTHESIS CATALYST IN A THREE-PHASE SLURRY REACTOR

In the liquid phase methanol synthesis process, syngas reacts in the presence.of fine catalyst particles slurried in the oil phase, in a three phase slurry reactor system. A method for activating high concentration ( ≤25 wt. %) of the CuO-ZnO-Al₂O₃ catalyst in the catalyst-oil slurry has been successfully developed. This catalyst activation process can be of crucial significance in the research and development of the methanol synthesis process in a liquid entrained reactor.

The reducing gas contains 2% hydrogen in nitrogen mixture and this activation procedure is carried out at a pressure of 125 psi. The catalyst-oil slurry is subjected to a controlled temperature ramping from 110° to 250° C. The catalyst has beemshown to be effectively reduced after following this activation procedure, that is valid especially for high catalyst loadings in slurry. Since the reduction is carried out in the process liquid medium and inside the reactor system, the catalyst-oil slurry after the treatment is ready for the synthesis of methanol.     

THERMAL EFFECT ON THE PERMANENT VISCOSITY OF A SASKATCHEWAN HEAVY OIL

Future energy demands will likely cause increased activity towards the recovery of heavy oil using non-conventional means. Most non-conventional attempts to recover Saskatchewan's heavy oil resources have utilized thermal techniques.

This report discusses the permanent viscosity changes which occur when heavy oil.is subjected to thermal processes from 220 to 425°C. It was observed that under closed operating conditions, the oil viscosity drops in a manner which can be modeled by a first order, kinetic reaction model. The rate constant for this reaction varied from 0.3 × 10^-3 to 6.0 × 10^-3 h^-1 depending on temperature and the assumed molecular weights of the model components. These findings closely parallel earlier results.

Experimental observations on thermal effects during opened operating conditions indicate a dramatic and rapid rise In the remaining crude oil viscosity. The oil was observed to increase its permanent absolute viscosity by a factor as high as 21 times its original absolute viscosity. The single product, first order kinetic model was not capable of predicting this rise in oil viscosity. A simple, two product, first order kinetic model was developed and found to fit the data satisfactorily with a rate constant of 0.6 h^-1 for heavy product formation and a rate constant of 0.03 h^-1 for light product formation at 275°C.     

EFFECTS OF HYDROTREATING COKER LIGHT GAS OIL ON FUEL QUALITY

Coker light gas oil (LGO) derived from Athabasca bitumen was hydrotreated in a fixed bed reactor using two commercial NiO-MoO₃/Al₂0₃ catalysts. The effect of temperature on product quality was investigated in a pilot plant between 330 and 390 °C at 12.4 MPa, space velocity of 0.5 Ir1 and 700 liter of hydrogen per liter of coker LGO (L/L). The product quality was monitored by ^I3C NMR spectroscopy, elemental analysis, density and distillation techniques.

The data showed that coker LGO can be hydrotreated using nickel-molybdenum catalysts at 350 °C, 0.5 h¹, 12.4 MPa and 700 L/L to meet the diesel product specifications, namely, 0.5 wt % sulfur, 20% aromatics and cetane index of 40. The cetane index improvement and aromatic saturation, which are affected by thermodynamic equilibrium at temperature higher than 370 °C, could reach 29 and 86% respectively. The cetane improvement was attributed to aromatic saturation and hydrocracking with hydrogen consumption ranging from 215-340 L/L. The Ketjenfine KF-840 catalyst was found slightly better performance than Procatalyse HR-348 catalyst.     

Survival of Campylobacter jejuni on vacuum or carbon dioxide packaged primal beef cuts stored at −1.5 °C

The ability of two Campylobacter jejuni strains (MOO3, a cattle isolate, and MOO8, a sheep isolate) to survive on chilled, preservatively packaged primal beef cuts was examined. Each of the strains was inoculated separately (10⁵ cfu g⁻¹) onto 500 g beef steaks, packaged under vacuum or 100% carbon dioxide, and stored, with uninoculated controls, for 41 days at −1.5 °C. Bacterial numbers were determined at 0, 1, 3, 6, 13, 20, 27, 34 and 41 days by dilution, plating on both Columbia Sheep Blood Agar and Campylobacter Blood-Free Selective Agar and incubation at 42 °C for 48 h under microaerophilic conditions. In addition, an aerobic count on all samples was determined by dilution, plating on Plate Count Agar and incubation at 25 °C for 72 h. No significant changes in numbers of the C. jejuni strains or aerobic bacteria occurred during storage at −1.5 °C on steaks packaged under either vacuum or carbon dioxide. The ability of these pathogens to survive standard preservative packaging conditions is different from that reported in the literature and therefore a cause for concern. Strict hygienic practice or the implementation of decontamination technologies are recommended as mechanisms to assure safety of meat with respect to this pathogen.     

REFORMING OF N-OCTANE ON A Pt/Al2O 3 CATALYST. 1. PRODUCT DISTRIBUTION AND KINETIC ANALYSIS.

The conversion of n-octane on Pt/Al₂O₃ catalyst to hydrocracked products, isooctane, ethylbenzene, o-,p-,m-xylene and toluene was investigated in hydrogen in a Berty CSTR at three different partial pressures of n-octane, 101·325 KPa total pressure, temperatures between 400°C-460°C and W/F values up to 0·33gmincm^-3. The hydrocracked products were the most predominant. Of the other products, isooctane was present in the highest yield. A sequence of elementary steps based on the suggested reaction network of Ako and Susu (1986) was found to predict the experimental conversion-W/F data with the conversion of adsorbed isooctane to adsorbed o-xylene as the rate determining step. The activation energies for the forward and backward reactions of this step were determined to be 21·2 and 14·3 Kcal/gmol, respectively.