This journal is c The Royal Society of Chemistry 2011 Catal. Sci. Technol. Cite this: DOI: 10.1039/c1cy00269d Ru-nanoparticle deposition on naturally available clay and rice husk biomass materials—Benzene hydrogenation catalysis and synthetic strategies for green catalyst development Omar Bin Shawkataly, a R. Jothiramalingam,* a F. Adam, b T. Radhika, b T. M. Tsao c and M. K. Wang c Received 13th July 2011, Accepted 23rd October 2011 DOI: 10.1039/c1cy00269d We demonstrate the rapid synthesis of ruthenium nanoparticle supported on naturally available isolated soil clay and ceria-modified rice husk silica biomass. Ruthenium nanoparticle deposition on nanoclay (clay particles of o100 nm) and on rice husk silica was performed via a high pressure hydrogenation process. A ruthenium organometallic compound was used as a precursor for ruthenium nanoparticle formation. The physico-chemical characteristics of the synthesized materials were analyzed by XRD, FT-IR, SEM-EDX and TEM analysis. The successful incorporation of ruthenium nanoparticle on nanoclay (Ru/Nanoclay-A) and on ceria-modified rice husk silica (Ru/Ce-RHS-B) was confirmed by XRD and FT-IR analysis. Ruthenium deposition on ceira-modified rice husk silica catalyst (Ru-Ce/RHS-C) has also been synthesized and characterized for a comparison study. The spherical shaped particles were observed between 60–80 nm for Ru/Nanoclay-A. However Ru/Ce-RHS-B and Ru-Ce/RHS-C material derived from biomass showed an aggregated morphology. Benzene hydrogenation under high pressure conditions has been studied in presence of the aforementioned three types of catalysts, Ru/Nanoclay-A, Ru/Ce-RHS-B and Ru-Ce/RHS-C. The Ru/Ce-RHS-B catalyst showed maximum conversion of 85% with selectivity of 72% towards cyclohexene formation, compared with other catalysts. 1. Introduction Development of non-toxic and rapid synthesis of low cost green catalysts from agricultural waste and biomass is growing field of interest. Rice husk ash (RHA) is a one of the major waste product of the rice milling industry and the silica content is known to be 94%. 1,2 The waste product generated from rice husk is commonly utilized for agricultural purposes, additives and as an reinforcing material. 3 The silica from rice husk ash can be easily extracted by an acid pretreatment process, which results in the formation of amorphous SiO 2 . 4 Silica generated from RHA (RHS) has been successfully used as a support material for various metal catalysis processes in the fine chemical industry. 5,6 Triangular triruthenium dodecacarbonyl-like organometallic complexes are proven to be efficient catalysts for carbonyl group reduction and hydrogenation of alkenes and arenes. 7–9 Bimetallic catalysts and nanoparticles derived from organo- metallic complexes are found to be more effective precursors due to ordered cluster arrangement and uniform particle size formation. 10 Liu et al. (2009) recently reported the ceria- promoted Ru-SBA-15 catalyst for hydrogenation of alkenes. Ruthenium chloride was used as the starting material to produce ruthenium deposition in the SBA-15 porous structure and subsequently tested for catalytic benzene hydrogenation. 11 Ning et al. (2006) reported colloidal ruthenium particles stabilized by silica, which were prepared by microemulsion processing and the catalyst was tested for selective benzene hydrogenation under high pressure condition. 12 Nanoparticles derived from metal carbonyls such as triruthenium dodeca- carbonyl could provide a more ordered and effective particle size for catalysis applications compared to conventional metal salt precursors. Iron and magnesium-enriched smectite (SYS) clay is derived from the natural black soil existing in eastern Taiwan. 13 The modified and isolated clay with a particle size of o100 nm is designated as nanoclay in the present study. The modified nanoclay (o100 nm clay particle) is obtained by a specific ultrafiltration device and details of the methodology for the isolation of clay with different nanoparticle sizes is reported elsewhere by our group. 14 a School of Distance Education, Universiti Sains Malaysia, P. Penang 11800, Malaysia. E-mail: rjothiram@gmail.com, omarsa@usm.my; Fax: (60)04-657-6000; Tel: (60)04-653-3539 b School of Chemical Sciences, Universiti Sains Malaysia, P. Penang 11800, Malaysia c Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan Catalysis Science & Technology Dynamic Article Links www.rsc.org/catalysis PAPER Downloaded on 02 December 2011 Published on 02 December 2011 on http://pubs.rsc.org | doi:10.1039/C1CY00269D View Online / Journal Homepage