In-situ CO2 utilization for dual production of hydrogen-rich gas and syngas via sorption-enhanced steam methane reforming chemical looping

A dual-purpose process is designed to produce hydrogen-rich gas (H2-rich gas) and syngas (H2/CO) via sorption- enhanced steam methane reforming chemical looping (SE-SMR-CL). The work focuses on improving process operation to be environmentally friendly and producing a value-added product by in-situ utilization of the byproduct carbon dioxide (CO2). Theoretical and experimental studies are used to determine suitable operating windows and investigate parametric effects on H2 and H2/CO production. The theoretical results reveal that 93.84 % H2 purity with low production of CO2 (1.91 %) can be obtained at 650 degrees C and 1 bar using a steam to carbon molar ratio (S/C) of 3 in the reforming step. A syngas molar ratio of 1.58 can be produced at 850 degrees C using a methane to calcium carbonate (CH4/CaCO3) molar ratio of 2 in the calcination step. Co-addition of steam enhances a syngas molar ratio up to 2, depending upon amount of the steam feed and operating temperature. The proof-of-concept was experimentally conducted using a multifunctional material Ni/CaO-Ca5Al6O14. The results show that 80 vol% H2 purity is obtained from the reforming step at S/C of 3, T of 650 degrees C, P of 1 bar, and Weight Hourly Space Velocity (WHSV) of 1800 ml/h gcat. A syngas ratio of ca. 1 at T of 850 degrees C and P of 1 bar can be produced during the calcination step. Co-addition of steam reduces carbon formation and increase syngas ratio to ca. 1.2-1.4. This developed technique can improve not only the existing steam reforming technology to be more environmentally friendly but also can enhance its value by co-production of H2/CO with different qualities, which can be applied for various applications.