High selective hydrocarbon and hydrogen products from catalytic pyrolysis of rice husk: Role of the ordered mesoporous silica derived from rice husk ash for Ni-nanocatalyst performance

• Published in: Journal of analytical and applied pyrolysis Vol. 178; p. 106383
• Main Authors: Pham, Le Kim Hoang, Alsaiari, Mabkhoot, T. Thu Thao, Bui, Hieu, Nguyen Huu, Phuc Hoang Duy, Nguyen, Vo, Dai-Viet N., Witoon, Thongthai, Nguyen, Van Cuong, Kongparakul, Suwadee, Samart, Chanatip, Trinh, Thanh H., Al-Gheethi, Adel
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-2024
• Subjects: Hydrogen; Nickel catalyst; Orders-silica; Pyrolysis; Rice husk; H2-TPR; BJH; Pluronic P123; Pyrolysis; Nickel catalyst; EG; Hydrogen; IUPAC; RHA; CTAB; HMS; BET; GC-MS; Rice husk; NH3-TPD; Orders-silica; EDS; RH; NIST; SEM; SAXD
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2024.106383

This study successfully synthesized ordered mesoporous silica using a sodium silicate solution derived from high-purity silica extracted from rice husk (98.09%), aiming to catalyst support for integrating fast catalytic upgrading of rice husk. The ordered mesoporous silica, including MCM-41 and KIT-6, were synthesized by co-assembly with additional surfactants, consisting of Cetyl trimethylammonium bromide (CTAB) and Pluronic P123, respectively. A series of 10 wt.% Ni on MCM-41 (Ni/HMS1) and KIT-6 (Ni/HMS2) were synthesized via ethylene glycol ultrasound-assisted wetness impregnation, which enhanced bio-oil quality by reducing oxygen compounds. This method also improved NiO reducibility up to 91.41%, with nickel phyllosilicate playing a pivotal role in preventing Ni-metallic sintering during the reduction process. The well-dispersed small Ni particles yielded high Ni performance in deoxygenation. Moreover, the order of pore size and structure of the hexagonal nanochannel structures influenced the selective hydrocarbon products in bio-oil. Ni/HMS1, with smaller pore sizes (3–5 nm), achieved a balanced hydrocarbon composition with aromatic (44.91%) and aliphatic (15.65%) components, while Ni/HMS2, having larger pores (8–10 nm), predominantly contained aromatic hydrocarbons (67.45%). The utilization of a green methodology for extracting high-value silica from biological sources promises to innovate and boost eco-consciousness in all rice husk pyrolysis products.
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•MCM-41 and KIT-6 synthesized from rice husk ash.•EG ultrasound-assisted impregnation of Ni on MCM-41 & KIT-6.•Silica-supported Ni catalysts applied upgrading rice husk pyrolysis.•Ni interaction with porous silica hinders the metal sintering.•Silica's structure and pore size regulate hydrocarbon selectivity.