Catalytic bi-reforming of methane for carbon dioxide ennoblement

6th International Conference on Energy and Environment Research (ICEER)New processes that may reduce the net carbon emissions and contribute to a more circular economy are needed. Bi-reforming of methane (BRM) is a promising method for syngas production, with a hydrogen-to-carbon monoxide ratio of two in the reaction products, relevant for example when the purpose is methanol synthesis. In this work, reaction studies were carried out over a nickel-based catalyst varying the temperature (798–1123 K). Three main temperature zones have been identified; a low temperature zone where the conversion of carbon dioxide is almost null, a middle temperature range where steam reforming of methane (SRM) is dominant while the conversion of carbon dioxide via dry reforming of methane (DRM) is low, and finally a high temperature range where DRM becomes more significant. The results show that syngas can be successfully produced using this process. For the range of operating conditions studied, the carbon dioxide and methane conversions increase with temperature, reaching 40% and 100%, respectively at the largest temperature studied. However, the production of syngas in a molar ratio of 1:2 for CO-to-H requires the use of high temperatures. Most probably the nickel agglomerates on top of the -alumina support are responsible for the poor catalyst performance.FCT, Portugal funded research grants SFRH/BPD/112003/2015, SFRH/BPD/105623/2015 and IF/01093/2014 and Center for Innovation in Engineering and Industrial Technology — CIETI, Portugal, UID/EQU/00305/2013. Project UID/EQU/00511/2019 - Laboratory for Process Engineering, Environment, Biotechnology and Energy — LEPABE funded by national funds through FCT/MCTES (PIDDAC), Portugal; Project “LEPABE-2-ECO-INNOVATION” – NORTE-01-0145-FEDER-000005, funded by Norte Portugal Regional Operational Programme (NORTE 2020), Portugal, under PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This work was financially supported by: Associate Laboratory LSRE-LCM, Portugal – UID/EQU/50020/2019 – funded by national funds through FCT/MCTES (PIDDAC), Portugal .info:eu-repo/semantics/publishedVersio

Catalytic bi-reforming of methane for carbon dioxide ennoblement

New processes that may reduce the net carbon emissions and contribute to a more circular economy are needed. Bi-reforming of methane (BRM) is a promising method for syngas production, with a hydrogen-to-carbon monoxide ratio of two in the reaction products, relevant for example when the purpose is methanol synthesis. In this work, reaction studies were carried out over a nickel-based catalyst varying the temperature (798-1123 K). Three main temperature zones have been identified; a low temperature zone where the conversion of carbon dioxide is almost null, a middle temperature range where steam reforming of methane (SRM) is dominant while the conversion of carbon dioxide via dry reforming of methane (DRM) is low, and finally a high temperature range where DRM becomes more significant. The results show that syngas can be successfully produced using this process. For the range of operating conditions studied, the carbon dioxide and methane conversions increase with temperature, reaching 40% and 100%, respectively at the largest temperature studied. However, the production of syngas in a molar ratio of 1:2 for CO-to-H-2 requires the use of high temperatures. Most probably the nickel agglomerates on top of the gamma-alumina support are responsible for the poor catalyst performance. (C) 2019 Published by Elsevier Ltd

Binary adsorption of CO2/CH4 in binderless beads of 13X zeolite

The binary sorption CO2 and CH4 in binderless beads of 13X zeolite has been investigated between 313 and 473 K and total pressure up to 5 atm through fixed bed adsorption experiments. The amount adsorbed of CO2 and CH4 is around 4.7 mmol/gads and 0.4 mmol/gads, respectively, at 313 K and 3.7 atm in a 50/50 equimolar mixture. In a 25(CO2)/75(CH4) mixture the amount adsorbed is 4.0 and 0.84 mmol/g at the same temperature and pressure. Experimental selectivities CO2/CH4 range from 37 at a low pressure of 0.667 atm to approximately 5 at the high temperature of 423 K. Comparing these values with the ones in literature CO2 adsorption capacity is 20% higher than in CECA 13X binder pellets. The CO2/CH4 binary isotherms were fitted with the extended Fowler model that takes into account interaction between adsorbed molecules at adjacent sites suggesting a moderate attraction between CO2 and CH4. The model is validated through a graphical method using the single component isotherm parameters. The breakthrough curves measured show a plateau of pure CH4 of approximately 6 min depending of the operating conditions chosen

High-Purity Hydrogen Production by Sorption-Enhanced Steam Reforming of Ethanol: A Cyclic Operation Simulation Study

A four-step pressure swing operation process in one column with two subsections for sorption-enhanced steam reforming of ethanol (SE-SRE) was developed by simulation for high purity hydrogen production. Within the two subsections, two different volumetric ratios (1:2 and 1:4) between the Ni impregnated hydrotalcite catalyst and K-promoted hydrotalcite sorbent were employed. Various reaction conditions and operating parameters were tested to improve the hydrogen production performance. The product gas with hydrogen purity above 99 mol % and carbon monoxide content of 30 ppm, which can be directly used in fuel cell applications, was continuously produced at 773 K and a swing pressure from 101.3 to 304 k Pa. The yield of hydrogen in SE-SRE (78.5%) was found to be much higher than in SRE (38.3%) at the same reaction conditions. Besides, pure carbon dioxide can also be obtained as a byproduct with a yield of 75% during the regeneration step

Methanol production by bi-reforming

Population growth and emerging economies have as consequence increasing energy demands associated with fossil fuel depletion and environmental impacts. A new philosophy emerges: the concept of green chemistry. Carbon dioxide, a well-known greenhouse gas, is a source for the production of fine chemicals and fuels such as methanol. It appears in abundance due to anthropogenic human activities. Nowadays, methanol is typically produced from synthesis-gas which requires conventional fossil fuels; however, the availability of these fuels is limited. As an alternative, the vent streams of steam reforming units, which are rich in carbon dioxide and steam, can be used together with methane (natural gas) in a bi-reforming process for methanol synthesis. The essential idea is that carbon dioxide and water are recycled like in a synthetic photosynthesis process

Adsorption equilibrium and dynamics of fixed bed adsorption of CH4/N2in binderless beads of 5A zeolite

The sorption equilibrium of methane (CH4) and nitrogen (N2) in binderless beads of 5A zeolite is presented between 305 and 373 K and pressures up to 3 bar in a static electronic microbalance. The adsorbed amount of CH4 and N2 is around 1.6 and 1.02 mol/kgads, respectively, at 305 K and 3 bar. A comparison of these values with the ones in literature shows that the adsorption capacity of the 5A binderless beads is 20% higher than that of the 5A binder commercial materials. The CH4 and N2 adsorption isotherms were fitted with the simplest Langmuir model with a prediction of the maximum amount adsorbed for both compounds of 5.0 mol/kg. The heats of sorption are -16.6 and -15.1 kJ/mol for CH4 and N2, respectively. In the overall pressure and temperature range the isotherms of N2 seems practically linear. However, it was observed that the experimental data of N2 at low coverage (below 0.2 bar) deviates slightly from Type I isotherms. Thereafter, the binary sorption of CH4 and N2 has been investigated in a fixed bed adsorber at 313 and 343 K and total pressures up to 5 bar for 50(CH4)/50(N2) and 75(CH4)//25(N2) mixture ratios diluted in an inert helium stream. A mathematical model was formulated to compute the dynamic behavior of the fixed bed adsorber using the extended binary Langmuir model, showing close agreement with the measured binary breakthrough experiments in the partial pressure range of the components above 0.2 and below 3 bar. © 2015 American Chemical Society

How to Overcome the Water-Gas-Shift Equilibrium using a Conventional Nickel Reformer Catalyst

The catalytic water-gas-shift (WGS) reaction into hydrogen and carbon dioxide was investigated using a commercial nickel reformer catalyst. The effects of temperature, flow rate, and catalyst nature on the course of reaction were evaluated. Hydrogen and carbon dioxide were generated in the temperature range between 125 and 475 degrees C. A reaction scheme was used to explain the formation of methane. The WGS reaction and the methanation reaction (MTN) were used to calculate the equilibrium composition at these conditions. A commercial hydrotalcite-like sorbent arranged in a multilayer pattern of catalyst plus sorbent was used for carbon dioxide capture to enhance the WGS reaction. The performance of the catalyst was assessed by comparing the measured conversions, hydrogen yields, and selectivities at steady-state conditions with equilibrium values and with selected results reported recently, as well as conversions, hydrogen yields, and selectivities during the transient period as the hybrid system consisting of catalyst plus sorbent is arranged in a multilayer pattern system. The multilayer pattern system consisting of catalyst plus sorbent can easily overcome the thermodynamic restrictions of the WGS reaction at an operating temperature of 400 degrees C because of the enhanced sorption effect during the reaction process. In addition, lower flow rate regimes, and higher pressures and steam/carbon ratios increase the initial breakthrough period. This sorption-enhanced technique makes the use of Ni-based catalysts for the WGS reaction attractive, and suitable for the adjustment of the hydrogen ratio in synthesis gas streams

Syngas production by bi-reforming of methane on a bimetallic Ni-ZnO doped zeolite 13X

Ennoblement of carbon dioxide, particularly the one produced by anaerobic digestion or by biomass combustion, is a motivation to develop novel or improving already existing processes. In this context, an interesting idea is to use carbon dioxide combined together with methane and water. Therefore, bi-reforming of methane (BRM) for syngas production appears to be a good choice. In this work, BRM was studied over a Ni-catalyst supported on a ZnO-doped zeolite 13X in the temperature range 300 to 900 ◦C. This material was deeply characterized by different techniques. The pure zeolite 13X shows relative good sorption capacity for CO2 at low temperatures (<100 ◦C). The ZnO phase introduced on zeolite 13X did not show a significant improvement for BRM, while 13X zeolite material impregnated with Ni and ZnO showed promising activities, achieving CO2 conversions in the range of 50–60% at a maximum operating temperature of 800 ◦C and atmospheric pressure. The results obtained suggest that ZnO acts as an oxygen supplier when methane is activated by surface nickel, thus destabilizing the feed in the following order: methane, water and carbon dioxide. The influence of the operating conditions in the reactants conversion and products distribution was also analyzed, and it can be concluded that the molar ratios of hydrogen-to-carbon monoxide are close to two at high temperatures.This work was financially supported by: Base Funding – UIDB/ 00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology and Energy – LEPABE – funded by national funds through the FCT/MCTES (PIDDAC) and Base Funding – UIDB/50020/2020 of the Associate Laboratory LSRE-LCM – funded by national funds through FCT/MCTES (PIDDAC). This work was also financially supported by the Spanish Project ref. RTI 2018-099224-B100 from ERDF/Ministry of Science, Innovation and Universities – State Research Agency and Nano4Fresh project (ref. PCI2020-112045), as part of the PRIMA Programme supported by the European Union. Authors thank Prof. Alírio Rodrigues (LSRE) and Prof. Jos´e Miguel Loureiro for supporting this research. AFC acknowledges the financial support from Fundaçao ˜ para a Cîˆencia e a Tecnologia (FCT, Portugal) via research grants SFRH/BPD/ 105623/2015, SFRH/BPD/112003/2015, and IF/01093/2014. SMT (RYC-2019-026634-I/AEI/10.13039/501100011033) and LMPM (RYC2016-19347) acknowledge the Spanish Ministry of Economy and Competitiveness (MINECO), the State Research Agency and the European Social Found for their Ramon ´ y Cajal research contracts. The authors are very grateful to Dr. Kristin Gleichmann, Chemiewerk Bad Kostritz ¨ GmbH, Germany, who kindly supplied the samples of binderless zeolite 13X (trade name “KOSTROLITH ¨ ® NaMSXK/13XBFK”) used in this work. Authors acknowledge for the free available software provided by the Martin-Luther-Universitat ¨ Halle-Wittenberg, Zentrum für Ingenieurwissenschaften (Prof. Dr. Dieter A. Lempe), and Hochschule Merseburg (FH), University of Applied Sciences, FB Ingenieurund Naturwissenschaften (Prof. Dr. Gerd Hradetzky), entitled “Thermodynamics of (Complicated) Chemical Reaction Equilibria”, weblink: http://physchem.hs-merseburg.de/.info:eu-repo/semantics/publishedVersio

High-Purity Hydrogen Production by Sorption-Enhanced Steam Reforming of Ethanol: A Cyclic Operation Simulation Study

A four-step pressure swing operation process in one column with two subsections for sorption-enhanced steam reforming of ethanol (SE-SRE) was developed by simulation for high purity hydrogen production. Within the two subsections, two different volumetric ratios (1:2 and 1:4) between the Ni impregnated hydrotalcite catalyst and K-promoted hydrotalcite sorbent were employed. Various reaction conditions and operating parameters were tested to improve the hydrogen production performance. The product gas with hydrogen purity above 99 mol % and carbon monoxide content of 30 ppm, which can be directly used in fuel cell applications, was continuously produced at 773 K and a swing pressure from 101.3 to 304 kPa. The yield of hydrogen in SE-SRE (78.5%) was found to be much higher than in SRE (38.3%) at the same reaction conditions. Besides, pure carbon dioxide can also be obtained as a byproduct with a yield of 75% during the regeneration step