Graphite Felt-Sandwiched Ni/SiC Catalysts for the Induction Versus Joule-Heated Sabatier Reaction: Assessing the Catalyst Temperature at the Nanoscale

Abstract

The paper describes a series of graphite felt (GF)-sandwiched k Ni/SiC composites at variable metal loading (k = 10, 15 and 20 wt.%) and their application as catalysts for the CO 2 methanation process (Sabatier reaction) under two distinct and conceptually different heating setup: Joule heating vs. Induction heating. A comparative analysis carried out on all catalysts from this series operated under the two heating configurations, has unveiled the superior performance of radiofrequency heated (IH) catalysts in the process. Most importantly, it has offered a practical tool to map the gap existing between the macroscopic temperature value measured at the catalyst bed by a remote-sensing thermometer (pyrometer) and that (real) of the excited metal nano-objects (Ni NPs) directly engaged in the radiofrequency-heated catalytic process. Besides the evident advantages of IH technology applied to the methanation process in terms of process rates () already under nominally low-reaction temperatures, the virtual absence of any thermal inertia and the subsequent fast modulation of the temperature at the catalytic bed, demonstrate unique features of this heating technology in terms of process safety (cold-reactor walls) and reduction of energy wastes (neither pre-and post-catalyst heating of reagents and products, nor that of the whole reactor volume and its peripheral walls).

Catalytic Sabatier Process under Thermally and Magnetically Induced Heating: A Comparative Case Study for Titania-Supported Nickel Catalyst

“…The temperature differences noted here for 5Ni/TiO 2 are in the range of temperature differences reported for 10Ni/SiC systems in the literature by Truong-Phuoc et al [39]. In the literature, Pham-Huu and their co-workers have thoroughly investigated the catalytic CO 2 methanation performances (% CO 2 conversion, % CH 4 selectivity versus temperature) under both induction heating and classical heating conditions [22,38,39,41]. It was reported that, at a given temperature, the catalytic % CO 2 conversion and %CH 4 selectivity values were higher for induction heating conditions than for classical heating.…”

“…Furthermore, with the low Ni loading and high heating capabilities of iron wool, the actual surface temperature of the Ni nanoparticles is perhaps slightly underestimated. The temperature differences noted here for 5Ni/TiO 2 are in the range of temperature differences reported for 10Ni/SiC systems in the literature by Truong-Phuoc et al [39]. In the literature, Pham-Huu and their co-workers have thoroughly investigated the catalytic CO 2 methanation performances (% CO 2 conversion, % CH 4 selectivity versus temperature) under both induction heating and classical heating conditions [22,38,39,41].…”

“…Unlike the thermally heated reactors, in the case of magnetic heating, it is difficult to measure the actual catalyst surface temperature by using a thermocouple. Hence, the average temperature noted at the top of the catalytic bed is slightly underestimated compared to the actual temperature of the core of the catalytic bed [23,32,[37][38][39]. The temperature difference (∆T) between thermal and magnetic induction heating was found to be ~30-40 • C to reach the same % CO 2 conversion (~20% conversion, within the kinetic regime) (Figure 5).…”

Improving catalytic performance via induction heating: selective oxidation of H2S on a nitrogen-doped carbon catalyst as a model reaction

“…Therefore, it can avoid the thermal decomposition of the reactants or intermediate compounds caused by overheating of the whole reactor [5,6]. Recently, IH mode has been reported as an efficient heating mode for operating catalytic processes with significant improved performance [6][7][8][9][10][11]. Alongside with the advantages cited above IH also represents a green heating mean for operating catalytic processes as it can be operated using exceeding renewable electricity, instead of using traditional fuel burner for providing heat to the reactor, which contributes to the reduction of CO2 for the process [6,12,13].…”

“…5,6 Recently, the IH mode has been reported as an efficient heating mode for operating catalytic processes with significantly improved performance. [6][7][8][9][10][11] Besides the abovementioned advantages, IH represents a green heating means for operating catalytic processes, as it can be operated using exceeding renewable electricity, instead of using a traditional fuel burner for providing heat to the reactor, which contributes to the reduction of CO 2 for the process. 6,12,13 Hydrogen sulfide (H 2 S), one of the major toxic and malodorous gases, is commonly emitted from chemical industries, such as natural gas refineries, crude oil, biogas purification and coal chemistry.…”