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

Abstract

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.

Dry Reforming of Methane over Ni-Supported SBA-15 Prepared with Physical Mixing Method by Complexing with Citric Acid

“…All the results were consistent with the previous results of XRD, TEM, and H 2 -TPR results. Moreover, as reported in the literature [40], the Ni/SBA-15 prepared by the acid-assisted co-impregnation method exhibited excellent stability within the testing time of 30 h, which was similar to the results in this work. The conversion of CH 4 and CO 2 in the above-mentioned literature was dependent on the concentration of citric acid used for the preparation of Ni/SBA-15.…”

“…The Ni particle size of Ni/SBA-15-M (17.2 nm) was clearly larger than that of Ni/SBA-15-M-C (8.1 nm) and Ni/SBA-15-I (7.8 nm). As reported in the literature [40], Ni/SBA-15 catalysts with Ni loading of 7% were prepared using the citric acid-assisted incipient wetness impregnation method. The authors found that the Ni particle size estimated by H 2 pulse chemisorption was in the range of 7.3-8.2 nm, which is dependent on the concentration of the citric acid used.…”

Tailoring Sepiolite for Efficient CO2 Desorption: A Sustainable Approach Utilizing Acid Activation for Amine Regeneration Optimization

“…As per the IUPAC classification of isotherms, it is noteworthy that all catalysts exhibited type IV isotherms accompanied by H4 hysteresis loops. These characteristics indicate the predominance of mesopores and slit-like pores, respectively. − Table provides insights into the surface area, revealing a substantial increase in the acid-activated SEP catalysts coupled with a modest enhancement in the pore volume. This observation underscores the efficacy of acid treatment in augmenting porosity.…”

Acetone Efficient Degradation under Simulated Humid Conditions by Mn–O–Pt Interaction Taming-Triggered Water Dissociation Intensification

“…24 Waris and Zhang et al also proposed that smaller Ni particles were found on SBA-15 by introducing citric acid through the impregnation method. 25,26 Until now, however, the noble metal loaded on the citric acid-assisted transition metal oxides/SiO 2 and their catalytic activity in the presence of H 2 O have not been reported. Moreover, the effect of citric acid on the electron transport property through the chemical bond interaction may play a key role in the catalytic activity in the presence of H 2 O, of which the method and mechanism also remain unclear.…”