Efficient and Stable Ni/SBA-15 Catalyst for Dry Reforming of Methane: Effect of Citric Acid Concentration

• Published in: Catalysts Vol. 13; no. 6; p. 916
• Main Authors: Waris, Mamoona, Ra, Howon, Yoon, Sungmin, Kim, Min-Jae, Lee, Kyubock
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.06.2023
• Subjects: Acids; Carbon dioxide; Catalysts; Catalytic converters; Chemical reactions; Chemical synthesis; Citric acid; Climate change; Conversion; dry reforming; Energy consumption; Greenhouse gases; mesoporous silica; Metals; Methane; Nanoparticles; nickel; Oxidation; Particle size; Reforming; Stability tests; Synthesis gas; Japan
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal13060916

Citric acid, one of the representative chelate compounds, has been widely used as an additive to achieve the highly dispersed metal-supported catalysts. This study aimed to investigate the effect of citric acid concentration on the preparation of the highly dispersed Ni catalysts on mesoporous silica (SBA-15) for the dry reforming of methane. A series of Ni/SBA-15 catalysts with citric acid were prepared using the acid-assisted incipient wetness impregnation method, and the Ni/SBA-15 catalyst as a reference was synthesized via the impregnation method. First of all, the citric acid addition during the catalyst synthesis step regardless of its concentration resulted in highly dispersed Ni particles of ~4–7 nm in size in Ni/SBA-15 catalysts, which had a superior and stable catalytic performance in the dry reforming of methane (93% of CO2 conversion and 86% of CH4 conversion). In addition, the amount of coke formation was much lower in a series of Ni/SBA-15 catalysts with citric acid (~2–5 mgcoke gcat−1 h−1) compared to pristine Ni/SBA-15 catalysts (~22 mgcoke gcat−1 h−1). However, when the concentration of citric acid became higher, the more free NiO species that formed on the SBA-15 support, leading to large Ni particles after the stability test. The addition of citric acid is a very clear strategy for making highly dispersed catalysts, but its concentration needs to be carefully controlled.