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Adesoji A. Adesina - One of the best experts on this subject based on the ideXlab platform.
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Influence of cycle parameters on periodically operated Fluidised Bed Reactor for CH4 autoreforming
Catalysis Today, 2000Co-Authors: Kingsley Opoku-gyamfi, Joaquim Vieira-dias, Adesoji A. AdesinaAbstract:Abstract Autothermal reforming of CH4 has been studied under both periodic and steady state conditions. The investigation was conducted over Co–NiO in a Fluidised Bed Reactor at 873 K and 101.32 kPa. Cycle periods of 1–40 min were used whilst the cycle split, Sox (with respect to the O2-rich cycle) was varied from 0.1 to 0.9. Generally, CH4 oxidation stimulated CO formation, however, steam reforming yielded predominantly CO2 and H2. Although O2-rich cycling (Sox≥0.5) was detrimental to H2 formation, H2O-rich cycling resulted in a 15% improvement in steady state H2 formation. Theoretical as well as experimental investigations pointed to a resonant frequency of about 6.7 mHz for CH4 oxidation to produce super steady state H2 yields. By periodic operation, it is possible to tune H2/CO ratios over the range 2.5–7 for the same feed composition. Interestingly, Sox=0.1 yielded the highest ratios, whereas the lowest ratios were attained at Sox=0.9. Periodic composition cycling introduces a more flexible approach to Reactor operation — H2/CO can be easily modulated by varying the cycle parameters — compared to steady state operation.
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kinetic studies of ch4 oxidation over pt nio δ al2o3 in a Fluidised Bed Reactor
Applied Catalysis A-general, 1999Co-Authors: K Opokugyamfi, Adesoji A. AdesinaAbstract:Abstract The oxidation of CH 4 over Pt–NiO/δ-Al 2 O 3 has been studied in a Fluidised Bed Reactor as part of a major project on an autothermal (combined oxidation–steam reforming) system for CH 4 conversion. The kinetic data were collected between 773 and 893 K and 101 kPa total pressure using CH 4 and O 2 compositions of 10–35% and 8–30%, respectively. Rate–temperature data were also obtained over alumina-supported monometallic catalysts, Pt and NiO. The bimetallic Pt–NiO system has a lower activation energy (80.8 kJ mol −1 ) than either Pt (86.45 kJ mol −1 ) and NiO (103.73 kJ mol −1 ). The superior performance of the bimetallic catalyst was attributed to chemical synergy. The reaction rate over the Pt–NiO catalyst increased monotonically with CH 4 partial pressure but was inhibited by O 2 . At low partial pressures ( 2 O has a detrimental effect on CH 4 conversion, whilst above 30 kPa, the rate increased dramatically with water content.
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Kinetic studies of CH4 oxidation over Pt–NiO/δ-Al2O3 in a Fluidised Bed Reactor
Applied Catalysis A-general, 1999Co-Authors: K Opoku-gyamfi, Adesoji A. AdesinaAbstract:Abstract The oxidation of CH 4 over Pt–NiO/δ-Al 2 O 3 has been studied in a Fluidised Bed Reactor as part of a major project on an autothermal (combined oxidation–steam reforming) system for CH 4 conversion. The kinetic data were collected between 773 and 893 K and 101 kPa total pressure using CH 4 and O 2 compositions of 10–35% and 8–30%, respectively. Rate–temperature data were also obtained over alumina-supported monometallic catalysts, Pt and NiO. The bimetallic Pt–NiO system has a lower activation energy (80.8 kJ mol −1 ) than either Pt (86.45 kJ mol −1 ) and NiO (103.73 kJ mol −1 ). The superior performance of the bimetallic catalyst was attributed to chemical synergy. The reaction rate over the Pt–NiO catalyst increased monotonically with CH 4 partial pressure but was inhibited by O 2 . At low partial pressures ( 2 O has a detrimental effect on CH 4 conversion, whilst above 30 kPa, the rate increased dramatically with water content.
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Fluidised Bed Reactor studies of H2S decomposition over supported bimetallic Ru catalysts
Catalysis Today, 1999Co-Authors: D. Cao, Adesoji A. AdesinaAbstract:Abstract H 2 S is produced in large quantities in the coal, petroleum and mineral processing industries. The decomposition of H 2 S to recover both salable sulphur and H 2 which may be recycled for further re-use in upstream hydrodesulphurisation (HDS) units is important in the context of zero-pollutant discharge. Several transition bimetallic sulphide catalysts (with Ru as a constant ingredient) were evaluated in a Fluidised Bed Reactor operated at 160 kPa and 883–1003 K. The Ru–Mo pair emerged as the “best” catalyst for H 2 production. The activity of the catalysts was well correlated with the same electronic and metal sulphur bond properties, A-character, seen for HDS reactions. The Ru–Mo catalyst exhibited a first order kinetics in H 2 S partial pressure with an activation energy of 69.7 kJ mol −1 . Due to thermodynamic limitations H 2 yields are low. This study shows that H 2 S conversions in a Fluidised Bed Reactor may be higher than those obtained from a fixed Bed configuration operating under same flow conditions. Indeed, conversions in the Fluidised Bed Reactor were higher than equilibrium values near minimum bubbling conditions at all the temperatures examined. However, as the flow rate increased beyond this point, conversion dropped significantly probably due to the onset of slugging. This improved conversion was attributed to the “membranous effect” in the Fluidised Bed since reaction occurs primarily in the emulsion phase and the migration rate of the relatively low molecular weight H 2 product from the catalyst-containing emulsion phase to the solid-free bubble phase helped to shift the reversible reaction in favour of hydrogen.
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Forced composition cycling of a novel thermally self-sustaining Fluidised-Bed Reactor for methane reforming
Chemical Engineering Science, 1999Co-Authors: Kingsley Opoku-gyamfi, Adesoji A. AdesinaAbstract:Abstract The novel coupling of methane oxidation and steam reforming via periodic composition forcing can be used to operate a thermally self-sustaining Fluidised-Bed Reactor. The autothermal reaction was carried out over an alumina-supported Co–NiO catalyst. The catalyst exhibited synergism for the steam reforming reaction although extent of synergy decreased from 3.2 at 773 K to 1.4 at 873 K. Analysis of steady-state oxidation and steam reforming rates showed that the bifunctional catalyst would favour H 2 production in a well-mixed Reactor at the lowest temperature permissible (773 K). Cycle symmetry, S OX , has to be greater than 0.3 to achieve thermal self-sustainability. However, time-average rate and H 2 yield increased with cycle frequency. Interestingly, even at the relatively low H 2 O:CH 4 molar ratio of 1, coking was practically non-existent probably due to carbon gasification via reaction with O 2 and H 2 O in the periodically-operated FBR. This investigation shows that the coupling of energetics, kinetics and Reactor operation may lead to serendipity in Reactor performance.
M H Yang - One of the best experts on this subject based on the ideXlab platform.
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chemical catalysed recycling of waste polymers catalytic conversion of polypropylene into fuels and chemicals over spent fcc catalyst in a Fluidised Bed Reactor
Polymer Degradation and Stability, 2007Co-Authors: M H YangAbstract:Polypropylene (PP) was pyrolysed over spent FCC commercial catalyst (FCC-s1) using a laboratory Fluidised-Bed Reactor operating isothermally at ambient pressure. The influence of reaction conditions including catalyst, temperature, and ratio of polymer to catalyst feed and flow rates of fluidising gas was examined. The yield of gaseous and liquid hydrocarbon products at 390 � C for spent FCC commercial catalyst (87.8 wt%) gave much higher yield than silicate (only 17.1 wt%). Greater product selectivity was observed with FCC-s1 as a post-use catalyst with about 61 wt% olefins products in the C3eC7 range. The selectivity could be further influenced by changes in reaction conditions. Valuable hydrocarbons of olefins and iso-olefins were produced by low temperatures and short contact times used in this study. It is also demonstrated that a post-use catalyst system under appropriate conditions the resource potential of polymer waste can be economically recovered and also can address the recycling desire to see an alternative to solve a major environment problem. 2007 Elsevier Ltd. All rights reserved.
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catalytic conversion of commingled polymer waste into chemicals and fuels over spent fcc commercial catalyst in a Fluidised Bed Reactor
Applied Catalysis B-environmental, 2007Co-Authors: M H YangAbstract:A commingled post-consumer polymer (CPW#1) was pyrolysed overspentfluid catalytic cracking (FCC) commercial catalyst (ECat-1) using a laboratory Fluidised-Bed Reactor operating isothermally at ambient pressure. The influence of reaction conditions including catalyst, temperature, ratios of commingled polymer to catalyst feed and flow rates of fluidising gas was examined. The conversion for spent FCC commercial catalyst (82.7 wt%) gave much higher yield than silicate (only 14.2 wt%) and the highest yield (nearly 87 wt%) was obtained for ZSM-5. Greater product selectivity was observed with ECat-1 as a recycled catalyst with about 56 wt% olefins products in the C3‐C7 range. The selectivity could be further influenced by changes in reaction conditions. Valuable hydrocarbons of olefins and iso-olefins were produced by low temperatures and short contact timesused inthis study. Itisalsodemonstrated that the useof spent FCCcommercial catalyst and underappropriate reaction conditionscan have the ability to control both the product yield and product distribution from polymer degradation, potentially leading to a cheaper process with more valuable products. # 2006 Elsevier B.V. All rights reserved.
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catalytic degradation of high density polyethylene over mesoporous and microporous catalysts in a Fluidised Bed Reactor
Polymer Degradation and Stability, 2004Co-Authors: Y H Lin, M H Yang, T F Yeh, M D GerAbstract:High density polyethylene (HDPE) was pyrolysed over various catalysts using a laboratory Fluidised-Bed Reactor operating isothermally at ambient pressure. HZSM-5 catalysed degradation resulted in much larger amounts of volatile hydrocarbons compared with degradation over non-zeolitic catalysts (MCM-41 and SAHA). When an HZSM-5 was used as a cracking additive in combination with a non-zeolitic catalyst (MCM-41 and SiO2–Al2O3), the solid mixed catalysts produced less gas with a lower loss of gasoline than HZSM-5. MCM-41 with large mesopores and SAHA with weaker acid sites resulted in a highly olefinic product and gave rise to the broadest carbon range of C3–C7. Both SAHA and MCM-41 materials allow bulky reactions to occur leading to the generation of coke and subsequently deactivation of the catalyst. This paper presents the conversion of polymers to useful hydrocarbons using various cracking catalysts and attempts to provide a basis for optimising the potential benefit of catalytic polymer recycling.
Zhengjian Wang - One of the best experts on this subject based on the ideXlab platform.
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Kinetic evaluation of an anaerobic Fluidised-Bed Reactor treating slaughterhouse wastewater
Bioresource Technology, 1995Co-Authors: Rafael Borja, Charles J. Banks, Zhengjian WangAbstract:An anaerobic Fluidised-Bed Reactor for purification of slaughterhouse wastewater was modelled as a continuous-flow, completely-mixed homogeneous microbial system, with the feed COD as the limiting-substrate concentration. The average microbial residence time in the Reactor was defined in terms of conventional sludge-retention-time. The experimental data obtained indicated that the Michaelis-Menten expression was applicable to a description of substrate utilisation (i.e. COD removal) in the anaerobic Fluidised-Bed system. The maximum substrate utilisation rate, k, and the Michaelis constant, Ks, were determined to be 1·2/day and 0·039 g/l. The observed biomass yield in the Reactor decreased with increasing sludge-retention-time. The specific methane production rate observed was a linear function of the specific substrate-utilisation rate.
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effect of organic loading rate on anaerobic treatment of slaughterhouse wastewater in a Fluidised Bed Reactor
Bioresource Technology, 1995Co-Authors: R Borja, Charles J. Banks, Zhengjian WangAbstract:COD removed efficiencies in the range 75·0NDASH;98·9% were achieved in an anaerobic Fluidised-Bed Reactor treating slaughterhouse wastewater, when evaluated at organic loading rates (OLR) of between 2·9 and 54·0 g COD/l.d, hydraulic retention times (HRT) of between 0·5 and 8 h and feed COD concentrations of between 250 and 4500 mg/l. More than 94% of feed COD could be removed up to OLR of about 27 g COD/l.d. Up to 0·320 litres of methane were produced per gram of COD removed and this methane production rate was independent of the OLR applied in this investigation. Volatile fatty acid (VFA) concentration in the Reactor increased sharply at an OLR of about 30 g COD/l.d and, therefore, sufficient alkalinity should be provided to prevent pH from dropping to an undesirable level. The anaerobic Fluidised-Bed system can be operated at a significantly higher liquid throughput than other previously reported systems while maintaining its excellent efficiency.
Peter T Clough - One of the best experts on this subject based on the ideXlab platform.
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investigation of the apparent kinetics of air and oxy fuel biomass combustion in a spouted Fluidised Bed Reactor
Chemical Engineering Research & Design, 2020Co-Authors: Peter T Clough, Edward J. AnthonyAbstract:Abstract A bench-scale spouted Fluidised-Bed Reactor was used to investigate the combustion kinetics of pulverised woody biomass under air and oxy-fuel atmospheres. Bed temperatures were in the range of 923−1073 K and O2 concentrations were varied from 20−35 vol%. The activation energies and apparent orders of reaction were calculated for air and oxy-fuel combustion by means of an nth order Arrhenius equation approach. Results indicated that the apparent order of reaction for both air and oxy-fuel combustion was approximately zero. The activation energies were calculated assuming a zero-order reaction mechanism and were averaged over all oxygen concentrations for air and oxy-fuel combustion and found to be 18.95 kJ/mol and 26.93 kJ/mol, respectively. The rate of combustion under oxy-fuel conditions was, on average, 37.5% higher compared to air combustion. The shrinking core model with a reaction-controlled step was found to accurately represent the biomass combustion reactions under both air and oxy-fuel conditions.
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Investigation of the apparent kinetics of air and oxy-fuel biomass combustion in a spout Fluidised-Bed Reactor
Chemical Engineering Research and Design, 2020Co-Authors: Yongliang Yan, Peter T Clough, Edward J. AnthonyAbstract:Abstract A bench-scale spouted Fluidised-Bed Reactor was used to investigate the combustion kinetics of pulverised woody biomass under air and oxy-fuel atmospheres. Bed temperatures were in the range of 923−1073 K and O2 concentrations were varied from 20−35 vol%. The activation energies and apparent orders of reaction were calculated for air and oxy-fuel combustion by means of an nth order Arrhenius equation approach. Results indicated that the apparent order of reaction for both air and oxy-fuel combustion was approximately zero. The activation energies were calculated assuming a zero-order reaction mechanism and were averaged over all oxygen concentrations for air and oxy-fuel combustion and found to be 18.95 kJ/mol and 26.93 kJ/mol, respectively. The rate of combustion under oxy-fuel conditions was, on average, 37.5% higher compared to air combustion. The shrinking core model with a reaction-controlled step was found to accurately represent the biomass combustion reactions under both air and oxy-fuel conditions.
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Hydrogen Production by Sorption Enhanced Steam Reforming (SESR) of Biomass in a Fluidised-Bed Reactor Using Combined Multifunctional Particles.
Materials (Basel Switzerland), 2018Co-Authors: Peter T Clough, Matthew E. Boot-handford, Liya Zheng, Zili Zhang, Paul S. FennellAbstract:The performance of combined CO2-sorbent/catalyst particles for sorption enhanced steam reforming (SESR), prepared via a simple mechanical mixing protocol, was studied using a spout-Fluidised Bed Reactor capable of continuous solid fuel (biomass) feeding. The influence of particle size (300–500 and 710–1000 µm), CaO loading (60–100 wt %), Ni-loading (10–40 wt %) and presence of dicalcium silicate support (22.6 wt %) on SESR process performance were investigated. The combined particles were characterised by their density, porosity and CO2 carrying capacity with the analysis by thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH) and mercury intrusion porosimetry (MIP). All experiments were conducted with continuous oak biomass feeding at a rate of 0.9 g/min ± 10%, and the Reactor was operated at 660 ± 5 °C, 1 atm and 20 ± 2 vol % steam which corresponds to a steam-to-carbon ratio of 1.2:1. Unsupported combined particles containing 21.0 wt % Ni and 79 wt % CaO were the best performing sorbent/catalyst particle screened in this study, when accounting for the cost of Ni and the improvement in H2 produced by high Ni content particles. SESR tests with these combined particles produced 61 mmol H2/gbiomass (122 g H2/kgbiomass) at a purity of 61 vol %. Significant coke formation within the feeding tube and on the surfaces of the particles was observed which was attributed to the low steam to carbon ratio utilised.
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Hydrogen Production by Sorption Enhanced Steam Reforming (SESR) of Biomass in a Fluidised-Bed Reactor Using Combined Multifunctional Particles
MDPI AG, 2018Co-Authors: Peter T Clough, Matthew E. Boot-handford, Liya Zheng, Zili Zhang, Paul S. FennellAbstract:The performance of combined CO2-sorbent/catalyst particles for sorption enhanced steam reforming (SESR), prepared via a simple mechanical mixing protocol, was studied using a spout-Fluidised Bed Reactor capable of continuous solid fuel (biomass) feeding. The influence of particle size (300–500 and 710–1000 µm), CaO loading (60–100 wt %), Ni-loading (10–40 wt %) and presence of dicalcium silicate support (22.6 wt %) on SESR process performance were investigated. The combined particles were characterised by their density, porosity and CO2 carrying capacity with the analysis by thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH) and mercury intrusion porosimetry (MIP). All experiments were conducted with continuous oak biomass feeding at a rate of 0.9 g/min ± 10%, and the Reactor was operated at 660 ± 5 °C, 1 atm and 20 ± 2 vol % steam which corresponds to a steam-to-carbon ratio of 1.2:1. Unsupported combined particles containing 21.0 wt % Ni and 79 wt % CaO were the best performing sorbent/catalyst particle screened in this study, when accounting for the cost of Ni and the improvement in H2 produced by high Ni content particles. SESR tests with these combined particles produced 61 mmol H2/gbiomass (122 g H2/kgbiomass) at a purity of 61 vol %. Significant coke formation within the feeding tube and on the surfaces of the particles was observed which was attributed to the low steam to carbon ratio utilised
Luca Di Felice - One of the best experts on this subject based on the ideXlab platform.
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catalytic biomass gasification simultaneous hydrocarbons steam reforming and co2 capture in a Fluidised Bed Reactor
Chemical Engineering Journal, 2009Co-Authors: Claire Courson, Luca Di Felice, Nader Jand, Katia Gallucci, Pier Ugo Foscolo, A KiennemannAbstract:Tars and CH 4 generated from biomass gasification processes contribute significantly to the energy content of the producer gas: catalytic tar and CH 4 steam reforming allows to clean the gaseous fuel and improve the H 2 yield; in addition, the use of a CO 2 sorbent minimises carbon oxides. As a result of the whole process, a H 2 rich fuel gas may be obtained. This experimental work is addressed to study the practical feasibility of such concepts, choosing CH 4 , toluene and 1-methyl naphthalene (1-MN) as biomass gasification key primary products. Ni is used as a catalyst for steam reforming, and dolomite as a sorbent for CO 2 capture. Two kinds of catalytic systems are tested as Bed material: a mixture of dolomite and commercial nickel catalyst, and a new Ni/dolomite combined catalyst and sorbent. The experimental investigations have been carried out in a fixed Bed microReactor and a bench scale Fluidised Bed Reactor rig. Both combinations of catalyst and sorbent are found to be very effective in tar removing, with conversion values near to 100% for the compounds tested; simultaneous C0 2 sorption reveals itself as the key process step, improving significantly the performance of the catalytic system that may then decrease considerably after sorbent saturation.