Common methods for preparing mesoporous carbon (MC)-supported metal oxide nanoparticles include chemical vapor deposition , sol-gel, hydrothermal, and microemulsion methods. It is necessary to first prepare carbon materials and thereafter load the metal oxide nanoparticles. In recent years, simple one-pot methods to prepare mesoporous carbon-supported metal and metal oxide nanoparticles has received a lot of attention. Inspired by the semi-closed method for preparing MC materials, in this study, we report a method for preparing MC-supported metal oxide nanoparticles in a single-step process in a muffle furnace after adding a one-step in situ synthesized precursor in a semi-closed system. The porous carbon-supported metal oxide nanoparticles prepared using this method have the advantages of a small particle size, uniform distribution, stable structure, and applicability to various metal oxides. The MoO 3 /MC catalysts prepared using this method exhibited excellent catalytic performance for the selective oxidation of benzyl alcohol. Only 5 mg of MoO 3 /MC-2 was used to convert 0.5 mmol benzyl alcohol to benzaldehyde in 2 mL DMSO with a conversion of 99% under air. The catalytic reaction is carried out at a high TON and TOF of 181 and 30.2 h −1 , respectively. Furthermore, the MoO 3 /MC catalysts exhibited high selectivity, wide substrate universality, and excellent stability.
Jaewon Jang,Eunchae Oh,Byung-Joo Kim,Young-Hoon Kim,Junghoon Yang,Jungpil Kim
This study investigated the efficient conversion of greenhouse gases (GHGs), CO 2 and CH 4 mixtures, into few-walled carbon nanotubes (FWCNTs) through an optimized single-step and dual-step chemical vapor deposition (CVD) process. In the single-step process for directly synthesizing FWCNTs from greenhouse gases, CO 2 concentration, gas flowrates, and H 2 addition were identified as factors influencing the growth of FWCNTs. It was demonstrated that minimizing the amounts of CO 2 and H 2 was essential for achieving complete CO 2 conversion because CO 2 acts as an oxidizing agent that hinders CNT growth, while an excess of H 2 disrupts the chemical equilibrium of the CO 2 conversion reaction, leading to side reactions that suppress FWCNTs formation. To overcome these limitations, a dual-step approach incorporating sequential catalytic reactions was developed. In the first step, the Ni/SiO 2 catalyst was utilized to facilitate CO 2 methanation, reducing CO 2 amounts while generating CH 4 -rich gas. In the second step, CH 4 pyrolysis was performed over the FeMo/MgO catalyst, enabling the growth of high-quality FWCNTs. This sequential configuration successfully synthesized FWCNTs under conditions previously unattainable in the single-step process, validating the effectiveness of the dual-step design. The strategic optimization of process parameters and sequential catalytic reactions established a viable route for converting GHGs into valuable FWCNTs.
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