| Summary: | A novel dual Ni-based catalytic process (DCP) to control the H<sub>2</sub>/CO ratio of 2 in the syngas product within one step at temperature <700 °C was created and constructed. With the sequence of the catalysts located in the single reactor, the endothermic combined steam and CO<sub>2</sub> reforming of methane (CSCRM) reaction and the exothermic ultra-high-temperature water–gas shift (UHT-WGS) reaction work continuously. During the process, the H<sub>2</sub>/CO ratio is raised suddenly at UHT-WGS after the syngas is produced from CSCRM, and CSCRM utilizes the heat released from UHT-WGS. Due to these features, DCP is more compact, enhances energy efficiency, and thus decreases the capital cost compared to reformers connecting with shift reactors. To prove this propose, the DCP tests were done in a fixed-bed reactor under various conditions (temperature = 500, 550, and 600 °C; the feed mixture (CH<sub>4</sub>, CO<sub>2</sub>, H<sub>2</sub>O, and N<sub>2</sub>) with H<sub>2</sub>O/(CH<sub>4</sub> + CO<sub>2</sub>) ratio = 0.33, 0.53, and 0.67). According to the highest CH<sub>4</sub> conversion (around 65%) with carbon tolerance, the recommended conditions for producing syngas with the H<sub>2</sub>/CO ratio of 2 as a feedstock of Fischer–Tropsch synthesis include the temperature of 600 °C and the H<sub>2</sub>O/(CH<sub>4</sub> + CO<sub>2</sub>) ratio of 0.53.
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