Synthesis of platinum-loaded zirconia on Fecralloy using composite plasma-polymerized films

Abstract

Summary form only given. In one hydrogen-based energy system, fuel cells utilize hydrogen and oxygen to produce electricity while reformers produce hydrogen from infrastructure fuels such as gasoline, diesel and natural gas. Reformers based on microchannel technology require a catalyst dispersed throughout a porous support, while the support must adhere to the substrate. In this work, support and catalyst were deposited (onto Fecralloy/sup /spl reg//) in alternate layers of plasma-polymerized platinum acetyl-acetonate and zirconium acetylacetonate, denoted Pt(acac)/sub 2/ and Zr(acac)/sub 4/, respectively. After exposing the composite organic film to heat treatment, most organic constituents were volatilized and platinum-loaded zirconia remained. The plasma reactor consisted of a 10 cm inside diameter Pyrex/sup /spl reg// tube evacuated to a base pressure of 5/spl times/10/sup -4/ Torr and surrounded by a 4-turn 13.56 MHz RF coil. Non-equilibrium, inductively-coupled plasma was generated by applying RF fields to a precursor vapor plume emanating from a heated sublimator crucible. Plasma processing took place directly in the precursor vapor without added carrier gas. Plasma-polymerization of the Pt(acac)/sub 2/ and Zr(acac)/sub 4/ resulted in deposition of organic film on the Fecralloy/sup /spl reg//. In a typical fabrication run, six 4 /spl mu/m thick layers of plasma-polymerized Pt(acac)/sub 2/ and nine 7 /spl mu/m thick layers of plasma-polymerized Zr(acac)/sub 4/ were interleaved and heat treated. The intermediate organic composite film and the final synthesized platinum-loaded support adhering to the Fecralloy/sup /spl reg// have been evaluated with profilometry, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), inductively coupled plasma-mass spectroscopy (ICP-MS) and a water gas shift (WGS) reactor. Cubic phase platinum and cubic phase zirconia have been detected on the Fecralloy/sup /spl reg//. This catalytic material had a measurable influence on carbon monoxide concentration in a WGS reactor in the temperature range 400-500/spl deg/C, thus demonstrating catalytic activity in this high temperature range.