Thermal and catalytic upgrading of a biomass‐derived oil in a dual reaction system

The thermal and catalytic upgrsding of bio‐oil to liquid fuels was studied at atmospheric pressure in a dual reactor system over HZSM‐5, silica‐alumina and a mixed catalyst containing HZSM‐5 and silica‐alumina. This bio‐oil was produced by the rapid thermal processing of the maple wood. In this work, the intent was to improve the catalyst life. Therefore, the first reactor containing no catalyst facilitated thermal cracking of blo‐oil whereas the second reactor containing the desired catalyst upgraded the thermally cracked products. The effects of process variables such as reaction temperature (350°C to 410°C), space velocity (1.8 to 7.2 h^?1) and catalyst type on the amounts and quality of organic liquid product (OLP) were investigated, In the case of HZSM‐5 catalyst, the yield of OLP was maximum at 27.2 wt% whereas the selectivity for aromatic hydrocarbons was maximum at 83 wt%. The selectivities towards aromatics and aliphatic hydrocarbons were highest for mixed and silica‐alumina catalysts, respectively. In all catalyst cases, maximum OLP was produced at an optimum reaction temperature of 370°C in both reactors, and at higher space velocity. The gaseous product consisted of CO and CO₂, and C₁‐C₆ hydrocarbons, which amounted to about 20 to 30 wt% of bio‐oil. The catalysts were deactivated due to coking and were regenerated to achieve their original activity.     

Catalytic conversion of canola oil to fuels and chemicals over various cracking catalysts

The catalytic conversion of canola oil to fuels and chemicals was studied over HZSM-5, H-mordenite, H-Y, silicalite, aluminum-pillared clay (AL-PILC) and silica-alumina catalysts in a fixed bed micro-reactor. The reactor was operated at atmospheric pressure, a temperature range of 375?500°C and weight hourly space velocity (WHSV) of 1.8 and 3.6 h^?1. An organic liquid product (OLP), light hydrocarbon gases and water were the major products. The objective was to maximize the amount of OLP and its hydrocarbon content as well as optimize the selectivity for gas phase olefinic hydrocarbons. In addition, the performance of each catalyst in terms of minimizing the coke formation was examined. Among the six catalysts, HZSM-5 gave the highest amount of OLP of 63 mass% at 1.8 WHSV and 400°C. The hydrocarbon content of this OLP product was 83.8 mass%. With the exception of silica-alumina and aluminum-pillared clay catalysts, the other catalysts gave high concentrations of aromatic hydrocarbons which ranged between 23.1–95.6 mass% of OLP. The gas products consisted mostly C₃ and C₄ hydrocarbons. Ethylene, propylene and butanes were some of the valuable hydrocarbon gases. The olefin/paraffin ratio of the gas products was highest for AL-PILC catalysts but it never exceeded unity. The results showed that it was possible to significantly alter the yield and selectivity for the different hydrocarbon products by using different catalysts or changing the catalyst functionality such as acidity, pore size and crystallinity. Reaction pathways based on these results are proposed for the conversion of canola oil     

Conversion of canola oil to various hydrocarbons over Pt/HZSM-5 bifunctional catalyst

Canola oil conversion was studied at atmospheric pressure over Pt/HZSM-5 catalyst (0.5 mass% Pt) in a fixed bed micro-reactor. The operating conditions were: temperature range of 400?500°C, weight hourly space velocity (WHSV) of 1.8 and 3.6 h^?1 and steam/oil ratio of 4. The objective was to optimize the amount of gasoline range hydrocarbons in the organic liquid product (OLP) and the selectivity towards olefins and isohydrocarbons in the gas product. The gas yields varied between 22–65 mass% and were higher in the presence of steam compared to the operation without steam. The olefin/paraffin mass ratio of C₂-C₄ hydrocarbon gases varied between 0.31–0.79. The isohydrocarbons/n-hydrocarbons ratio was higher with Pt/HZSM-5 (1.6–4.8) compared with pure HZSM-5 catalyst (0.2–1.0). The OLP yields with Pt/HZSM-5 (20–55 mass% of canola oil) were slightly lower compared to HZSM-5 (40–63 mass% of canola oil) under similar conditions. The major components of OLP were aliphatic and aromatic hydrocarbons. A scheme postulating the reaction pathways for the conversion of canola oil over Pt/HZSM-5 catalyst is also presented.     

Catalytic conversion of canola oil to fuels and chemical feedstocks: Part II Effect of co-feeding steam on the performance of HZSM-5 catalyst

Ca lola oil and steam were co-fed continuously to a 15.5 mm i.d. fixed-bed reactor loaded with HZSM-5 catalyst at varying process conditions. The liquid hydrocarbon product contained 60–70 wt% aromatics. The gas product was highly olefinic, while for canola oil alone it was mostly paraffinic. The C₂-C₅ olefin selectivity increased with an increase in the steam/canola oil ratio in the feed. In addition, co-feeding with steam resulted in a two-fold increase in the catalyst life. Though the exact role of steam in altering the chemistry of the reaction is not known, it is probable that the rates of olefin formation and aromatization reactions are affected by the presence of steam. The product pattern suggests the possibility of propene being the initial olefin in the reaction scheme.     

Oxidative dehydrogenation of n-butane on V/MgO catalysts. Influence of the type of contactor

A comparative study of the catalytic performance of a selective V-Mg-O catalyst in the oxidative dehydrogenation of n-butane is presented using three different types of reactor: (i) an adiabatic fixed-bed reactor; (ii) a fluidized-bed reactor; and (iii) an in situ redox fluidized-bed reactor. The results obtained indicate that the in situ redox fluidized-bed reactor outperforms the conventional fixed- and fluidized-bed reactors, especially at high n-butane conversions. Thus, a selectivity to C₄ olefins of 54% at n-butane conversions of 60% was achieved at 550°C using an in situ redox fluidized-bed reactor while selectivities to C₄-olefins lower than 43% were obtained on the other reactor types under the same reaction conditions (isoconversion and reaction temperature). This revised version was published online in July 2006 with corrections to the Cover Date.     

Selective Production of C4 Hydrocarbons from Syngas Using Fe‐Co/ZrO2 and SO42—/ZrO2 Catalysts

Modified Fischer‐Tropsch (MFT) syntheses were carried out to convert synthesis gas to C₄ hydrocarbons over Fe‐Co/ZrO₂ (FT) and SO₄^2—/ZrO₂ (SZ) catalysts in a dual reactor system, keeping the FT to SZ catalysts ratio at 1:1.5. Five Fe‐Co/ZrO₂ catalysts with different Fe and Co loading, and SZ with 15 wt% SO₄^2— were prepared and extensively characterized using various physico‐chemical methods. The FT synthesis process was initially performed using a Fe‐Co/ZrO₂ catalyst in a single reactor and the effects of Fe and Co mass ratio, reaction temperature, space velocity on the production of C₄ hydrocarbons and C₂‐C₄ olefins were investigated. Results indicated that a 3.71% Fe—8.76% Co/ZrO₂ mixed oxide catalyst alone at 260°C and 5 h^—1 gave high selectivities of C₂‐C₄ olefins (～26.1 wt%) and total C₄ hydrocarbon product (～16.2 wt%). The MFT process 150°C gave higher C₄ (～31.6 wt%), isobutane (～22.9 wt%) and C₂‐C₄ (31.1 wt%) selectivities.     

Hydroprocessed rapeseed oil as a source of hydrocarbon-based biodiesel

This paper deals with the hydroprocessing of rapeseed oil representing a perspective technological way for production of biocomponents in diesel fuel range. Rapeseed oil was hydroprocessed at various temperatures (260-340 °C) under a pressure of 7 MPa in a laboratory flow reactor. Three Ni-Mo/alumina hydrorefining catalysts were used. Reaction products were analyzed using several gas-chromatographic methods. Reaction products contained water, hydrogen-rich gas and organic liquid product (OLP). The main components of OLP were identified as C₁₇ and C₁₈n-alkanes and i-alkanes. At a low reaction temperature, OLP contained also free fatty acids and triglycerides. At reaction temperatures higher than 310 °C, OLP contained only hydrocarbons of the same nature as hydrocarbons present in diesel fuel. Influence of reaction temperature and catalyst on the composition of reaction products is discussed.     

Catalytic conversion of canola oil to fuels and chemical feedstocks Part I. Effect of process conditions on the performance of HZSM-5 catalyst

The conversion of canola oil to hydrocarbons using a shape selective zeolite catalyst is reported in this work. Canola oil was passed over HZSM-5 catalyst in a fixed bed micro-reactor and the effects of reaction temperature and oil space velocity on the conversion and selectivity were studied using a statistical experimental design. The results show that 60–95 wt% of the canola oil can be converted to hydrocarbons in the gasoline boiling range, light gases and water. The gasoline fraction contained 60–70 wt% of aromatic hydrocarbons and the gases were mostly C₃ and C₄ paraffins. Furthermore, the spent catalyst could be regenerated completely at 600°C in 1 h with dry air.     

The catalytic conversion of CO2 to hydrocarbons over Fe–K supported on Al2O3–MgO mixed oxides

Al₂O₃–MgO mixed oxides prepared by a co-precipitation method have been used as supports for potassium-promoted iron catalysts for CO₂ hydrogenation to hydrocarbons. The catalysts have been characterized by XRD, BET surface area, CO₂ chemisorption, TPR and TPDC techniques. The CO₂ conversion, the total hydrocarbon selectivity, the selectivities of C₂–C₄ olefins and C₅₊ hydrocarbons are found to increase with increase in MgO content upto 20 wt% in Fe–K/Al₂O₃–MgO catalysts and to decrease above this MgO content. The TPR profiles of the catalysts containing pure Al₂O₃ and higher (above 20 wt%) MgO content are observed to contain only two peaks, corresponding to the reduction of Fe₂O₃ to Fe⁰ through Fe₃O₄. However, the TPR profile of 20 wt% MgO catalyst exhibits three peaks, which indicate the formation of iron phase through FeO phase. The TPDC profiles show the formation of three types of carbide species on the catalysts during the reaction. These profiles are shifted towards high temperatures with increasing MgO content in the catalyst. The activities of the catalysts are correlated with physico-chemical characteristics of the catalysts. This revised version was published online in July 2006 with corrections to the Cover Date.     

Hydrogenation of CO on supported cobalt γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst in fixed bed and slurry bubble column reactors

Fischer-Tropsch synthesis for the production of C₅+ hydrocarbons from syngas was carried out in a tubular fixed bed reactor (TFBR) and in a slurry bubble column reactor (SBCR). The Co-based catalysts for FTS were prepared by the conventional wet-impregnation of γ-Al₂O₃. Effects of operating conditions such as GHSV (1,000–4,000 ml/g·hr), reaction temperature (220–250°C) and pressure (0.5–3.0MPa) on the CO conversion and product selectivity of Co/γ-Al₂O₃ catalyst were examined in the TFBR and SBCR. The C₅+ selectivity and olefin selectivity in an SBCR were found to be higher than that in a TFBR, whereas C₂–C₄ selectivity showed a reverse trend. The CO conversion and product distribution in an SBCR were less sensitive than that in a TFBR with variations of reaction conditions.     

Steady-state conversion of methane to C4+ aliphatic products in high yields using an integrated recycle reactor system

Conversion of methane in high yields to C₄₊ nonaromatic hydrocarbons was demonstrated in a recycle system. The principal components of the recycle system included an oxidative coupling reactor with a Mn/Na₂WO₄/SiO₂ catalyst at 800°C for conversion of methane to ethylene, and a reactor with an H-ZSM-5 zeolite at 275°C for subsequent conversion of ethylene to higher hydrocarbons. Total yields of C₄₊ products were in the range of 60–80%, and yields of C₄₊ nonaromatic hydrocarbons were in the range of 50–60%. This revised version was published online in July 2006 with corrections to the Cover Date.     

Catalytic Pyrolysis of Pine Wood Sawdust to Produce Bio-oil: Effect of Temperature and Catalyst Additives

In this work, non-catalytic pyrolysis of Turkish pine (Pinus brutia Ten.) wood sawdust was performed in a fixed-bed reactor at various temperatures to obtain the optimum conditions to achieve a maximum bio-oil yield. The highest yield of bio-oil was obtained about 46 wt% at 550°C for non-catalytic pyrolysis. At the optimum conditions, the effects of different catalyst types (KOH, ZnCl₂, and ZnO) and amount of catalyst (5, 10, 15, and 20 wt%) on the pyrolysis product yields and bio-oil properties were investigated. The presence of catalysts changed the product distribution considerably. Increasing the amount of catalyst led to a decrease in the yield of liquid product, while the gas and char yields increased compared to non-catalytic pyrolysis. The chemical compositions of bio-oil were determined with GC-MS analyses. It was determined that bio-oils contain a large variety of organic compounds, such as furans, aldehydes, ketones, phenols, acids, benzenes, alcohols, alkanes, and polycyclic aromatic hydrocarbons (PAHs). The catalysis by KOH significantly increased the levels of phenols, while it reduced the formation of acids and aldehydes. ZnCl₂ produced bio-oil with high percentages of aldehydes. Moreover, ZnO reduced the proportion of PAH in the bio-oil. These results demonstrated that bio-oils could improve with a catalyst. Therefore, catalyst selection for high bio-oil quality is crucial in industrial applications.     

Enhanced Production of C2–C4 Olefins Directly from Synthesis Gas

An attempt made for the selective production of C₂–C₄ olefins directly from the synthesis gas (CO + H₂) has led to the development of a dual catalyst system having a Fischer–Tropsch (K/Fe–Cu/AlOx) catalyst and cracking (H-ZSM-5) catalyst operate in consecutive dual reactors. The flow rate (space velocity) and H₂/CO molar ratio of the feed have been optimized for achieving higher CO conversions and olefin selectivities. The selectivity to C₂–C₄ olefins is further enhanced by optimizing the reaction temperature in the second reactor (cracking), where the product exhibited 51% selectivity to C₂–C₄ hydrocarbons rich in olefins (77%) with a stable time-on-stream performance in a studied period of 100 h.     

Performance of combined cobalt—nickel—zirconia and HZSM-5 catalyst systems for carbon monoxide hydrogenation

The synthesis of hydrocarbons via hydrogenation of carbon monoxide was investigated over cobalt—nickel—zirconia catalysts of various compositions in combination with zeolite HZSM-5 in “mixed bed” and “follow bed” arrangements. These combinations resulted in the formation of aromatics in amounts as high as 30-35 wt% under relatively mild operating conditions (1 atm, 250–280°C). Although the olefinicity of C₂ and C₃ fractions in the product stream was higher in the mixed bed compared to the follow bed arrangement, the selectivities to aromatics were comparable in the two bed arrangements. The aromatic selectivity was found to be sensitive to operating conditions. The formation of aromatics was favored at high HZSM-5/metal catalyst ratios, low space velocities and high reaction temperatures. The product distributions obtained using various metal/zeolite bifunctional catalysts have been discussed.     

Selective oxidation of methane with air over silica catalysts

Partial oxidation of methane by oxygen to form formaldehyde, carbon oxides, and C₂ products (ethane and ethene) has been studied over silica catalyst supports (fumed Cabosil and Grace 636 silica gel) in the 630–780 °C temperature range under ambient pressure. The silica catalysts exhibit high space time yields (at low conversions) for methane partial oxidation to formaldehyde, and the C₂ hydrocarbons were found to be parallel products with formaldehyde. Short residence times enhanced both the C₂ hydrocarbons and formaldehyde selectivities over the carbon oxides even within the differential reactor regime at 780 °C. This suggests that the formaldehyde did not originate from methyl radicals, but rather from methoxy complexes formed upon the direct chemisorption of methane at the silica surface at high temperature. Very high formaldehyde space time yields (e.g., 812 g/kg cat h at the gas hourly space velocity = 560 000 (NTP)/kg cat h) could be obtained over the silica gel catalyst at 780 °C with a methane/air mixture of 1.5/1. These yields greatly surpass those reported for silicas earlier, as well as those over many other catalysts. Low CO₂ yields were observed under these reaction conditions, and the selectivities to formaldehyde and C₂ hydrocarbons were 28.0 and 38.8%, respectively, at a methane conversion of 0.7%. A reaction mechanism was proposed for the methane activation over the silica surface based on the present studies, which can explain the product distribution patterns (specifically the parallel formation of formaldehyde and C₂ hydrocarbons).     

Liquid products of the hydropyrolysis of brown coal form the Lena basin

Liquid hydrocarbon products were obtained by the hydropyrolysis of brown coal from a deposit in the northern Lena basin on an iron-containing catalyst. The individual and group compositions of gasoline and diesel fractions were determined with the use of capillary chromatography and chromatography-mass spectrometry. The gasoline fraction with a boiling point to 180°C was characterized by a high octane number; it mainly contained monocyclic aromatic hydrocarbons and normal alkanes. The diesel fraction mainly consisted of bi- and tricyclic aromatic hydrocarbons and C₁₃–C₁₉ n-alkanes.     

The electrochemical hydrogenation of edible oils in a solid polymer electrolyte reactor. II. Hydrogenation selectivity studies

Soybean oil has been hydrogenated electrochemically in a solid polymer electrolyte (SPE) reactor at 60°C and 1 atm pressure. These experiments focused on identifying cathode designs and reactor operation conditions that improved fatty acid hydrogenation selectivities. Increasing oil mass transfer into and out of the Pd-black cathode catalyst layer (by increasing the porosity of the cathode carbon paper/cloth backing material, increasing the oil feed flow rate, and inserting a turbulence promoter into the oil feed flow channel) decreased the concentrations of stearic acid and linolenic acid in oil products [for example, an iodine value (IV) 98 oil contained 12.2% C_18:0 and 2.3% C_18:3]. When a second metal (Ni, Cd, Zn, Pb, Cr, Fe, Ag, Cu, or Co) was electrodeposited on a Pd-black powder cathode, substantial increases in the linolenate, linoleate, and oleate selectivities were observed. For example, a Pd/Co cathode was used to synthesize an IV 113 soybean oil with 5.3% stearic acid and 2.3% linolenic acid. The trans isomer content of soybean oil products was in the range of 6–9.5% (corresponding to specific isomerization indices of 0.15–0.40, depending on the product IV) and did not increase significantly for high fatty acid hydrogenation selectivity conditions.     

Synthesis of Biodiesel from Canola Oil Using Heterogeneous Base Catalyst

A series of alkali metal (Li, Na, K) promoted alkali earth oxides (CaO, BaO, MgO), as well as K₂CO₃ supported on alumina (Al₂O₃), were prepared and used as catalysts for transesterification of canola oil with methanol. Four catalysts such as K₂CO₃/Al₂O₃ and alkali metal (Li, Na, K) promoted BaO were effective for transesterification with >85 wt% of methyl esters. ICP-MS analysis revealed that leaching of barium in ester phase was too high (~1,000 ppm) when BaO based catalysts were used. As barium is highly toxic, these catalysts were not used further for transesterification of canola oil. Optimization of reaction conditions such as molar ratio of alcohol to oil (6:1–12:1), reaction temperature (40–60 °C) and catalyst loading (1–3 wt%) was performed for most efficient and environmentally friendly K₂CO₃/Al₂O₃ catalyst to maximize ester yield using response surface methodology (RSM). The RSM suggested that a molar ratio of alcohol to oil 11.48:1, a reaction temperature of 60 °C, and catalyst loading 3.16 wt% were optimum for the production of ester from canola oil. The predicted value of ester yield was 96.3 wt% in 2 h, which was in agreement with the experimental results within 1.28%.     

A comparative study of combination of Fischer–Tropsch synthesis reactors with hydrogen-permselective membrane in GTL technology

This work proposes a one dimensional heterogeneous model to analyze the performance of combination of Fischer–Tropsch synthesis (FTS) reactors in which a fixed-bed reactor is combined with a membrane assisted fluidized-bed reactor. This model is used to compare the performance of the proposed system with a fixed-bed singlestage reactor. In the new concept, the synthesis gas is converted to FT products in two catalytic reactors. The first reactor is water-cooled fixed-bed type while the second reactor is gas-cooled and fluidized-bed. Due to the decrease of H₂/CO to values far from optimum reactants ratio, the membrane concept is suggested to control hydrogen addition. Moreover, a fluidized-bed system has been proposed to solve some observed drawbacks of industrial fixed-bed reactors such as high pressure drop, heat transfer problem and internal mass transfer limitations. This novel concept which has been named fluidized-bed membrane dual-type reactor is used for production of gasoline from synthesis gas. The reactor model is tested against the pilot plant data of the Research Institute of Petroleum Industry. Results show an enhancement in the gasoline yield, a main decrease in CO₂ formation and a favorable temperature profile along the proposed concept.     

H.p.l.c. quantitation of hydrocarbon class types in cracked products

H.p.l.c. was optimized to obtain quantitative compositional data on hydrocarbon class type (saturates, olefins, aromatics plus polars) in cracked products from vacuum gas oil (370–500°C) feed over REY zeolite catalyst in a micro-activity test unit. H.p.l.c. separation was achieved using an amino column, a backflush device and nC₆ as mobile phase. An RI detector was used to obtain total saturates and aromatics and a 200 nm u.v. detector to estimate olefins and aromatic hydrocarbons by ring number. Quantitation was achieved using external standard procedure and standards were prepared from the identical petroleum products to obtain response factors. A considerable variation in the liquid product yield during cracking reactions was noticed, from 40 to 70 wt%. Cracking reactions were also favoured through hydrogen transfer, increasing substantially the aromatic content in the range 50–70 wt%. Olefins were also formed during cracking, ranging from 5 to 10 wt%.