화학공학소재연구정보센터
Industrial & Engineering Chemistry Research, Vol.42, No.14, 3230-3236, 2003
Gas-phase hydrogenation of o-xylene over Pt/knitted silica-fiber catalysts
A knitted silica fiber was prepared and employed as a support material for platinum catalysts. Different knitted silica-fiber supported platinum catalysts were prepared using several platinum precursors. The catalysts were characterized by N-2 physisorption, H-2 adsorption, NH3/H-2/o-xylene temperature-programmed desorption, scanning electron microscopy - energy-dispersive X-ray analysis, and X-ray photoelectron microscopy. Catalyst activity was investigated in the gasphase hydrogenation of o-xylene at 360-460 K with o-xylene and hydrogen partial pressures of 0.06 and 0.36-0.73 bar. High o-xylene conversions (up to 99%) to cis- and trans-1,2dimethylcyclohexane were achieved. The specific surface area and pore volume of the support and the platinum precursor affected the catalyst performance. A catalyst prepared from platinum nitrate with a metal loading of 5 wt% exhibited the highest hydrogenation activity. A maximum in hydrogenation activity vs temperature was observed, which was caused by decreased surface o-xylene coverage with a temperature increase. Residual surface chlorine was found to affect both the catalyst activity and the product stereoselectivity. The selectivity toward the formation of trans-1,2-dimethylcyclohexane is increased at higher operation temperatures.