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Synthesis Gas (synthesis + gas)
Selected AbstractsReforming diesel-fuel distillates with membrane reactorsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Michael V. Mundschau Abstract A porous-membrane reactor is used to produce H2 and CO by dry partial oxidation of volatile hydrocarbons distilled from diesel fuel. To eliminate deposition of thermodynamically and kinetically favored carbon onto reactor walls as the fuel is heated, cool air is brought into reactors through porous walls of refractory, zirconia-based ceramic. Flow of air through reactor walls suppresses alkyl-radical polymerization that otherwise leads to formation of tar and soot in the reformer heating zone. Diesel fuel is distilled just below 200 °C to avoid cracking of long-chain n -alkanes. The volatile distillates enter the reformer in the vapor phase, eliminating need for complex liquid-fuel injectors and mixers. Volatile distillates are relatively easily reformed, eliminating soot and most naphthalene in the exhaust, converting 88 mole% of carbon in the distillate into CO, 7% into CH4, and 5% into CO2. Approximately 75 mole% of the hydrogen is converted into H2, 13% into CH4, and the remainder into H2O. Synthesis gas produced from diesel fuel distillates could fuel solid-oxide fuel cells or regenerate NOx traps used in pollution control. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Self-sustained reformation of diesel fuel using a SiC block with penetrating wallsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2010Min Kook Ko Abstract Reformation of diesel fuel was performed using a silicon carbide (SiC) block with penetrating walls. The atomized fuel was spray injected to the electrically heated block. The fuel,air mixture was reformed by partial oxidation and changed to synthesis gas including CO, CO2, H2O, O2 and H2. The composition of the reformed gas was measured with varying fuel,air ratios. The degree of reformation or conversion changes with the temperature and a maximum conversion efficiency of ,90% is attained at around 850°C. Copyright © 2009 John Wiley & Sons, Ltd. [source] Millisecond catalytic reforming of monoaromatics over noble metalsAICHE JOURNAL, Issue 4 2010C. M. Balonek Abstract The millisecond autothermal reforming of benzene, toluene, ethylbenzene, cumene, and styrene were independently studied over five noble metal-based catalysts: Pt, Rh, Rh/,-Al2O3, Rh,Ce, and Rh,Ce/,-Al2O3, as a function of carbon-to-oxygen feed ratio. The Rh,Ce/,-Al2O3 catalyst exhibited the highest feedstock conversion as well as selectivities to both synthesis gas and hydrocarbon products (lowest selectivities to H2O and CO2). Experimental results demonstrate a high stability of aromatic rings within the reactor system. Benzene and toluene seem to react primarily heterogeneously, producing only syngas and combustion products. Ethylbenzene and cumene behaved similarly, with higher conversions than benzene and toluene, and high product selectivity to styrene, likely due to homogeneous reactions involving their alkyl groups. Styrene exhibited low conversions over Rh,Ce/,-Al2O3, emphasizing the stability of styrene in the reactor system. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Synergistic routes to liquid fuel for a petroleum-deprived futureAICHE JOURNAL, Issue 7 2009Rakesh Agrawal Abstract When compared with biomass gasification/Fischer-Tropsch synthesis, hydropyrolysis/hydrodeoxygenation (HDO)-based processes have a potential to achieve high biomass carbon conversion to liquid fuel with much lower amounts of supplementary H2. On the basis of this observation, we suggest a Hydrogen Bio-oil (H2Bioil) process using fast hydropyrolysis/HDO that has a potential to produce nearly double the amount of liquid fuel when compared with the existing biofuel processes while requiring only modest quantities of supplementary H2. The optimal operating mode for the H2Bioil process is suggested to be in an entrained bed mode in presence of H2 with gas phase HDO of hydropyrolyzed vapors. A remarkable result due to reduced need for the supplementary H2 is that it provides synergistic integration of the H2Bioil process with a coal gasification power plant or a small scale steam natural gas (NG) reformer leading to a dramatic increase in the liquid fuel production from biomass and coal or NG. Here, hot synthesis gas (T>500°C) from a coal gasifier or methane reformer supplies H2/CO for hydropyrolysis and deoxygenation as well as heat for the process. This result is exciting, because it presents us with an option to build integrated H2Bioil processes sooner rather than later when the cost effective H2 becomes available from a carbon-free energy source such as solar or nuclear. The H2Bioil process and its integrated version with a small scale NG reformer have strong potential to be attractive on a small scale while being more efficient than any current biomass to liquid fuel process in operation. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] The water-gas shift reaction: from conventional catalytic systems to Pd-based membrane reactors,a reviewASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010D. Mendes Abstract The water-gas shift (WGS) reaction is a well-known step for upgrading carbon monoxide to hydrogen in the production of synthesis gas. For more than 90 years after its first industrial application, many issues in respect of the catalyst, process configuration, reactor design, reaction mechanisms and kinetics have been investigated. More recently, a renewed interest in the WGS reaction carried out in hydrogen perm-selective membrane reactors (MRs) has been observed because of the growing use of polymeric electrolyte membrane (PEM) fuel cells that operate using high-purity hydrogen. Moreover, MRs are viewed as an interesting technology in order to overcome the equilibrium conversion limitations in traditional reactors. This article reviews the most relevant topics of WGS MR technology,catalysis and membrane science. The most used catalysts and relevant progress achieved so far are described and critically reviewed. The effects of the most important parameters affecting the WGS in MRs are detailed. In addition, an overview on the most used membranes in MRs is also presented and discussed. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Green biorefinery demonstration plant in Havelland (Germany),BIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 3 2010Birgit Kamm Abstract The Green Biorefinery (GBR) is a complex and full-integrated system of environment- and resource-protecting technologies for comprehensive material and energetic use of green biomasses. GBR's are multiproduct systems and perform and produce in accordance with the physiology of the corresponding plant material preserving and using the diversity of the synthesis generated by nature. In addition to the general biorefinery concept, GBR's are based strongly on sustainable principles (sustainable land use, sustainable raw materials, gentle technologies, autarkic energy supply, etc.). Existing agricultural structures of the green crop processing industry, such as green crop drying plants, offer good opportunities for the implementation of biorefinery technologies that will help overcoming energy-intensive and partially obsolete technologies, such as the thermal drying of feedstock. Accordingly, the primary fractionation of green biomasses and the integrated production of proteins, fermentation media, animal feed, and biogas was projected and will be realized in a demonstration facility directly linked to the existing green crop drying plant, Selbelang, in Havelland (Germany, state Brandenburg, 50 km west of Berlin). The primary refinery will have an annual capacity of 20 000 tons alfalfa and grass biomass and can be diversified in modules for the production of platform chemicals and synthesis gas. We discuss the processes, products, operating costs and climate protection effects through examination of the basic engineering of the primary refinery. The production site and planned demonstration facility are also presented. Copyright © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd [source] A review of biogas purification processesBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 1 2009Nicolas Abatzoglou Abstract Biogas is a valuable renewable energy carrier. It can be exploited directly as a fuel or as a raw material for the production of synthesis gas and/or hydrogen. Methane (CH4) and carbon dioxide (CO2) are the main constituents, but biogases also contain significant quantities of undesirable compounds (contaminants), such as hydrogen sulfide (H2S), ammonia (NH3) and siloxanes. The existence and quantities of these contaminants depend on the biogas source (i.e., landfills, anaerobic fermentation of manure). Their presence constitutes a major problem because (i) they can be detrimental to any biogas thermal or thermocatalytic conversion device (e.g., corrosion, erosion, fouling); and (ii) they generate harmful environmental emissions. It is therefore important to include biogas purification steps upstream of its final use processes. This review is aimed at presenting the scientific and technical state-of-theart in biogas purification processes. Both mature, already-applied and promising, under-development technologies are reported and described here. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd [source] Growth of Rhodospirillum rubrum on synthesis gas: Conversion of CO to H2 and poly-,-hydroxyalkanoateBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2007Young S. Do Abstract To examine the potential use of synthesis gas as a carbon and energy source in fermentation processes, Rhodospirillum rubrum was cultured on synthesis gas generated from discarded seed corn. The growth rates, growth and poly-,-hydroxyalkanoates (PHA) yields, and CO oxidation/H2 evolution rates were evaluated in comparison to the rates observed with an artificial synthesis gas mixture. Depending on the gas conditioning system used, synthesis gas either stimulated or inhibited CO-oxidation rates compared to the observations with the artificial synthesis gas mixture. Inhibitory and stimulatory compounds in synthesis gas could be removed by the addition of activated charcoal, char-tar, or char-ash filters (char, tar, and ash are gasification residues). In batch fermentations, approximately 1.4 mol CO was oxidized per day per g cell protein with the production of 0.75 mol H2 and 340 mg PHA per day per g cell protein. The PHA produced from R. rubrum grown on synthesis gas was composed of 86% ,-hydroxybutyrate and 14% ,-hydroxyvalerate. Mass transfer of CO into the liquid phase was determined as the rate-limiting step in the fermentation. Biotechnol. Bioeng. 2007;97: 279,286. © 2006 Wiley Periodicals, Inc. [source] Carbon Monoxide Mass Transfer for Syngas Fermentation in a Stirred Tank Reactor with Dual Impeller ConfigurationsBIOTECHNOLOGY PROGRESS, Issue 3 2007Andrew J. Ungerman This study compares the power demand and gas-liquid volumetric mass transfer coefficient, kLa, in a stirred tank reactor (STR) (T = 0.211 m) using different impeller designs and schemes in a carbon monoxide-water system, which is applicable to synthesis gas (syngas) fermentation. Eleven different impeller schemes were tested over a range of operating conditions typically associated with the "after large cavity" region (ALC) of a Rushton-type turbine (D/T = 0.35). It is found that the dual Rushton-type impeller scheme exhibits the highest volumetric mass transfer rates for all operating conditions; however, it also displays the lowest mass transfer performance (defined as the volumetric mass transfer coefficient per unit power input) for all conditions due to its high power consumption. Dual impeller schemes with an axial flow impeller as the top impeller show improved mass transfer rates without dramatic increases in power draw. At high gas flow rates, dual impeller schemes with a lower concave impeller have kLa values similar to those of the Rushton-type dual impeller schemes but show improved mass transfer performance. It is believed that the mass transfer performance can be further enhanced for the bottom concave impeller schemes by operating at conditions beyond the ALC region defined for Rushton-type impellers because the concave impeller can handle higher gas flow rates prior to flooding. [source] Co-current and Countercurrent Configurations for a Membrane Dual Type Methanol ReactorCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2008R. Rahimpour Abstract A dynamic model for a membrane dual-type methanol reactor was developed in the presence of catalyst deactivation. This reactor is a shell and tube type where the first reactor is cooled with cooling water and the second one with feed synthesis gas. In this reactor system, the wall of the tubes in the gas-cooled reactor is covered with a palladium-silver membrane which is only permeable to hydrogen. Hydrogen can penetrate from the feed synthesis gas side into the reaction side due to the hydrogen partial pressure driving force. Hydrogen permeation through the membrane shifts the reaction towards the product side according to the thermodynamic equilibrium. Moreover, the performance of the reactor was investigated when the reaction gas side and feed gas side streams are continuously either co-current or countercurrent. Comparison between co-current and countercurrent mode in terms of temperature, activity, methanol production rate as well as permeation rate of hydrogen through the membrane shows that the reactor in co-current configuration operates with lower conversion and also lower permeation rate of hydrogen but with longer catalyst life than does the reactor in countercurrent configuration. [source] Preparation of Ni-Based Metal Monolithic Catalysts and a Study of Their Performance in Methane Reforming with CO2CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 6 2008Kai Wang Abstract A series of Ni/SBA-15/Al2O3/FeCrAl metal monolithic catalysts with Ni loadings varying between 3,% and 16,% were prepared, and their structure was characterized by various techniques. The catalytic activity of the catalyst for methane reforming with CO2 leading to synthesis gas was evaluated using a fixed-bed reactor. The results indicate good catalytic activity of the Ni/SBA-15/Al2O3/FeCrAl samples under the reaction conditions. The catalyst with a Ni loading of 8.0,% displays excellent activity and stability at 800,°C over 1400,h time on stream. After reaction, the hexagonal mesoporous structure of SBA-15 is still present and the pore walls of SBA-15 prevent the aggregation of nickel. Interactions between NiO, SBA-15, and the Al2O3/FeCrAl support modify the redox properties of the Ni/SBA-15/Al2O3/FeCrAl catalysts. [source] | |||||||||||||||||||||||||