Selective CO Methanation Over Ru Supported on Carbon Spheres: The Effect of Carbon Functionalization on the Reverse Water Gas Shift Reaction

Abstract

Mesoporous carbon spheres (CSs-H) were hydrothermally synthesised using sugar as carbon source. The as-synthesized CSs-H was microporous but after thermal treatment at 900 °C for 4 h it became mesoporous (surface area of 463 m 2 g −1 ). Further treatment of the annealed CSs-H with HNO 3 gave a functionalized CSs-H with a high defect content in the carbon matrix which resulted in an increase in surface area (509 m 2 g −1 ). The functionalized and un-functionalized CSs-H were used to support nano Ru particles for CO, CO 2 and selective CO methanation reactions. The Ru supported catalysts were prepared using both impregnation and microwave polyol synthesis methods. It was evident from the reduction studies that the functional groups on the surface of the CSs-H influenced the reduction of the RuO 2 to Ru. The catalyst with smaller and well dispersed RuO 2 particles (d = 2.7 nm) (prepared by the microwave polyol technique) gave a high activity in both CO and selective CO methanation studies. The larger Ru particles observed on the un-functionalized CSs-H showed poor activity for CO and selective CO methanation reactions and also did not promote the reverse water gas shift reaction. Graphical Abstract

Stability of Ruthenium/Carbon Catalytic Materials during Operation in Carbon Monoxide Methanation Process

“…Similar conclusions were reported by Eckle [16]. Although ruthenium catalysts supported on carbon materials exhibit promising properties [20][21][22][23], there is a lack of reports concerning the thermostability of ruthenium systems supported on carbon carriers. A La-doped 10 wt.% Ru/C1 catalyst exhibited stable activity during 72 h of overheating at 300 • C, which indicates satisfactory thermal resistance of La-Ru/carbon systems [23].…”

“…To compare the present activity results with other ruthenium catalysts supported on carbon materials, let us refer to Kumi [22]. Catalysts containing 5 wt.% of Ru supported on different carbon spheres were tested in a mixture of 1% CO and 89% H 2 (balance N 2 ), in the temperature range between 100 and 360 • C (1 g sample) [22].…”

“…To compare the present activity results with other ruthenium catalysts supported on carbon materials, let us refer to Kumi [22]. Catalysts containing 5 wt.% of Ru supported on different carbon spheres were tested in a mixture of 1% CO and 89% H 2 (balance N 2 ), in the temperature range between 100 and 360 • C (1 g sample) [22]. All the catalysts presented by Kumi [22] completely converted CO within a temperature range of 240-300 • C. In the case of Ru6/C2, complete CO conversion was reached at 270 • C (Figure S1b).…”

“…Catalysts containing 5 wt.% of Ru supported on different carbon spheres were tested in a mixture of 1% CO and 89% H 2 (balance N 2 ), in the temperature range between 100 and 360 • C (1 g sample) [22]. All the catalysts presented by Kumi [22] completely converted CO within a temperature range of 240-300 • C. In the case of Ru6/C2, complete CO conversion was reached at 270 • C (Figure S1b). However, it should be noted that the weight of the catalyst used in the present study was four times lower than that described in [22].…”

Influence of the Microstructure of Ni–Co Bimetallic Catalyst on CO Methanation

“…CO methanation, a process of methane synthesis from syngas, involves two reactions (eqs and ). − Thermodynamic analysis displays that low temperature is favorable for the reactions. However, the reactions are limited by chemical kinetics at low temperature.…”