Session: 17-01-01: Research Posters

Paper Number: 148147

148147 - Co-Production of High-Quality Hydrogen and Carbon Monoxide via Chemical Looping Dry Reforming of Methane 

Due to increased atmospheric CO2 concentration causing global warming, CO2 capture, sequestration, and utilization become important issues. Conversion of CO2 into CO is one of the important routes in CO2 utilization. CO can be mixed with H2 to form syngas with various H2/CO ratios for the fuel and chemical syntheses. However, CO2 is a chemically stable species that is difficult to convert into CO, even in high temperatures.

Hydrogen production from various types of fuels has received extensive study owing to its environmental sustainability, renewability, and clean energy. Hydrogen is also vital in chemical industries as a reactant. Based on the material source and carbon emission, hydrogen production can be classified into four categories. Grey hydrogen uses fossil fuels as raw materials and is currently the main way to produce hydrogen, accounting for about 95% of global hydrogen production. However, CO2 is inevitably emitted during the production process.

The dry reforming of methane (CH4+CO22CO+2H2) is a chemical process that consists of converting methane and carbon dioxide, identified as the world's most abundant greenhouse gases, to syngas, with an H2/CO molar ratio of 1. As a result, this process can potentially mitigate the environmental challenges associated with greenhouse gas emissions and convert biogas and natural gas to syngas. Moreover, the lower H2/CO ratio syngas produced is convenient for the production of hydrocarbons via Fischer-Tropsch synthesis. However, catalyst deactivation occurs in the reaction process because of methane decomposition and carbon deposition on the active catalyst surface sites.

To prevent catalyst deactivation, the chemical looping dry reforming of methane using CH4 as the reduction agent, CO2 as the oxidation agent, and NiO/Al2O3 as the oxygen carrier, was proposed for CO and H2 productions. In this system, CH4 is decomposed into H2 and carbon (CH42H2+C) in the fuel (reduction) reactor, which is deposited on the catalysts. In the air (oxidation) reactor, deposited carbon is oxidized by CO2 into CO (CO2+C2CO). The system has advantages in that it results in producing CO and H2 separately, which makes it possible to produce syngas of any composition. Additional advantages are provided in terms of CO2 activation and this system could help resolve environmental and energy issues.

For a reaction temperature of 900C and molar ratio CO2/CH4 of 1/1, the test result of CLDRM showed that over 90% CH4 and CO2 conversions can be reached. This implies that highly pure CO and H2 can be obtained separately from the air and fuel reactors. By increasing the reactant molar ratio CO2/CH4=2/1, or higher, almost 100% CH4 can be reached. This implies that theoretical yields of H2 can be obtained. With increased CO2 introduced into the air reactor, theoretical CO yield can be obtained. However, CO2 conversion is decreased due to excess CO2 amount introduced.          

Presenting Author: Rei-Yu Chein National Chung Hsing University

Presenting Author Biography: Dr. Rei-Yu Chein received his doctoral degree in mechanical engineering from Washington State University in 1986. Afterward, he joined the Mechanical Engineering Department of National Chung Hsing University (NCHU) in Taiwan as an Associate Professor. His early research work focused on gas-particle flows, micro-nano scale transport phenomena, and electronic cooling. Since 2005, he switched his research topics to energy-related areas such as hydrogen/syngas production, greenhouse gases/waste conversion and re-utilization, energy conversion system analysis, and fuel synthesis. He has published over 80 energy-related technical papers. Dr. Chein currently serves as a professor at NCHU. His teaching courses include thermodynamics, energy conversion, convective heat transfer, viscous fluid flow, and numerical analysis.

Authors:

Cheng-Wei Hong National Chung Hsing University
Rei-Yu Chein National Chung Hsing University