Utilization of CO2 for syngas production by CH4 partial oxidation using a catalytic membrane reactor.

Shehu, Habiba; Gobina, Edward; Orakwe, Ifeyinwa

Abstract

In this research, a synthetic flue gas mixture with added methane was used as the feed gas in the process of dry reforming with partial oxidation of methane using a laboratory scale catalytic membrane reactor to produce hydrogen and carbon monoxide that can present the starting point for methanol or ammonia synthesis and Fischer-Tropsch reactions. 0.5% wt% Rh catalyst was deposited on a γ-alumina support using rhodium (III) chloride precursor and incorporated into a shell and tube membrane reactor to measure the yield of synthesis gas (CO and H2) and conversion of CH4, O2 and CO2 respectively. These measurements were used to determine the reaction order and rate of CO2. The conversion of CO2 and CH4 were determined at different gas hourly space velocities. The reaction order was determined to be a first-order with respect to CO2. The rate of reaction for CO2 was found to follow an Arrhenius equation having an activation energy of 49.88 × 10−1 kJ mol−1. Experiments were conducted at 2.5, 5 and 8 ml h−1 g−1 gas hourly space velocities and it was observed that increasing the hourly gas velocities resulted in a higher CO2 and CH4 conversions while O2 conversion remained fairly constant. CO2 had a high conversion rate of 96% at 8 ml h−1 g−1. The synthesized catalytic membrane was characterized by Scanning Electron Microscopy (SEM) and the Energy Dispersive X-ray Analysis (EDXA) respectively. The micrographs showed the Rh particles deposited on the alumina support. Single gas permeation of CH4, CO2 and H2 through the alumina support showed that the permeance of H2 increased as the pressure was increased to 1 × 105 Pa. The order of gas permeance was H2 (2.00 g/mol) > CH4 (16.04 g/mol) > N2 (28.01 g/mol) > O2 (32 g/mol) > CO2 (44.00 g/mol) which is indicative of Knudsen flow mechanism. The novelty of the work lies in the combination of exothermic partial oxidation and endothermic CO2 and steam reforming in a single step in the membrane reactor to achieve near thermoneutrality while simultaneously consuming almost all the greenhouse gases in the feed gas stream.

Citation

SHEHU, H., GOBINA, E. and ORAKWE, I. 2019. Utilization of CO2 for syngas production by CH4 partial oxidation using a catalytic membrane reactor. International journal of hydrogen energy [online], 44(20), pages 9896-9905. Available from: https://doi.org/10.1016/j.ijhydene.2019.02.102

• Journal Article Type: Article
• Acceptance Date: Feb 13, 2019
• Online Publication Date: Mar 13, 2019
• Publication Date: Apr 19, 2019
• Deposit Date: Apr 9, 2019
• Publicly Available Date: Mar 14, 2020
• Journal: International Journal of Hydrogen Energy
• Print ISSN: 0360-3199
• Electronic ISSN: 1879-3487
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 44
• Issue: 20
• Pages: 9896-9905
• DOI: https://doi.org/10.1016/j.ijhydene.2019.02.102
• Keywords: Fuel gas; Carbon dioxide; Methane hydrogen; Carbon monoxide; Rhodium catalyst and membrane reactorechnology; Condensed matter physics
• Public URL: https://rgu-repository.worktribe.com/output/235485
• Contract Date: Apr 11, 2019