Developing Benign Ni/g-C₃N₄ Catalysts for CO₂ Hydrogenation: Activity and Toxicity Study

Abstract

This research discusses the CO 2 valorization via hydrogenation over the non-noble metal clusters of Ni and Cu supported on graphitic carbon nitride (g-C 3 N 4 ). The Ni and Cu catalysts were characterized by conventional techniques including XRD, AFM, ATR, Raman imaging, and TPR and were tested via the hydrogenation of CO 2 at 1 bar. The transition-metal-based catalyst designed with atom-economy principles presents stable activity and good conversions for the studied processes. At 1 bar, the rise in operating temperature during CO 2 hydrogenation increases the CO 2 conversion and the selectivity for CO and decreases the selectivity for methanol on Cu/CN catalysts. For the Ni/CN catalyst, the selectivity to light hydrocarbons, such as CH 4 , also increased with rising temperature. At 623 K, the conversion attained ca. 20%, with CH 4 being the primary product of the reaction (CH 4 yield >80%). Above 700 K, the Ni/CN activity increases, reaching almost equilibrium values, although the Ni loading in Ni/CN is lower by more than 90% compared to the reference NiREF catalyst. The presented data offer a better understanding of the effect of the transition metals’ small metal cluster and their coordination and stabilization within g-C 3 N 4 , contributing to the rational hybrid catalyst design with a less-toxic impact on the environment and health. Bare g-C 3 N 4 is shown as a good support candidate for atom-economy-designed catalysts for hydrogenation application. In addition, cytotoxicity to the keratinocyte human HaCaT cell line revealed that low concentrations of catalysts particles (to 6.25 μg mL –1 ) did not cause degenerative changes.

Efficient CO2 methanation using nickel nanoparticles supported mesoporous carbon nitride catalysts

“…All of the samples revealed a hump peak at 25.9°, which is compatible with the g-C 3 N 4 characteristic peak, which may be ascribed to the MCN (002) reflection plane 64 . This peak, in particular, is indicative of MCN's graphitic origin because it is a characteristic of graphitic materials 58 . As a consequence, because it is allocated from the planes generated by the agglutination of the connected aromatic groups in the layered structure, it is evidence of MCN and graphene's layered structural similarities 65 , 66 .…”

“…Substantial studies on CO 2 thermal methanation employing monometallic nickel-doped mesoporous carbon nitride revealed low performance, needing more inquiry and development to reach the greatest CO 2 conversion Percentage as well as flawless CH 4 selectivity. Izabela S. Pieta et al study's exemplifies ongoing research into the performance of Ni-doped carbon nitride in CO 2 methanation 58 . According to Izabela S. Pieta et al, under atmospheric pressure, CO 2 conversion and selectivity for light hydrocarbons, such as methane, increase as the temperature rises.…”

“…Because of its unique features for a range of applications in lucrative domains such as electro- 53 , basic-, and photocatalysis 53 , supercapacitor 54 , energy storage 55 , conversion 56 , and sensing 57 , MCN has long attracted the curiosity of specialists. Following that, even though MCN has been extensively investigated and demonstrated to have a perfect performance in the field of photocatalytic CO 2 conversion due to its unique properties in addition to its semiconductivity, mesoporous carbon nitride (gmp-C 3 N 4 ) has not been extensively studied in the thermal hydrogenation of CO 2 58 . In contrast to the other investigated applications for MCN, the utilization of Ni-doped mesoporous carbon nitride in thermal CO 2 methanation is regarded as relatively recent.…”

Ultrasonic-assisted synthesis of porous S-doped carbon nitride ribbons for photocatalytic reduction of CO2

“…Researchers have devised a variety of CO 2 reduction strategies, including thermochemical [2] , electrochemical [3] , and photochemical methods [4] . Methanol, carbon monoxide, ethylene, and other compounds can be produced from CO 2 [5] , [6] , [7] But the development of catalysts for CO 2 photo-reduction is still lagging due to a lack of effective, reliable, cost-effective, and highly selective catalysts.…”

Preface for Special Issue on Engineered Methodologies for CO2 Utilization

“…Focusing now on CO 2 transformation using green hydrogen, Tsubaki et al reported the direct conversion of CO 2 to aromatics using a bifunctional zeolite-based catalyst, Herskovitz et al. investigated the process configuration and technoeconomic aspect of CO 2 hydrogenation to renewable liquid fuels, Fan et al reported the conversion of CO 2 to light olefins using metal oxides, Pieta et al discussed the conversion of CO 2 to CO and methane using non-noble-metal-supported catalysts, Wang et al reported the conversion of CO 2 to methanol using a modified Cu/ZnO/Al 2 O 3 catalyst, Ma et al provided a short review on the formation of methanol from CO 2 by direct and indirect hydrogenation pathways, Gonzalez-Velasco et al investigated kinetics, model discrimination, and parameters of CO 2 methanation, Ding et al and Benito et al studied the mechanism of CO 2 methanation and promoter effect on the catalyst performance. For the transformation of CO 2 using chemicals other than green hydrogen, Ateka et al reported the joint conversion of CO 2 with syngas to synthesize light olefins, Liang et al and Sun et al prepared nickel-based catalysts for CO 2 reforming of methane, Jin et al investigated carbon fixation via the gasification of polypropylene and polycarbonate in a CO 2 environment, Song et al revealed mechanistic insights into the promotional effect of CO 2 on propane aromatization, and Liu et al reported enhanced CO 2 decomposition via frosted dielectric barrier discharge plasma .…”