Microfibrous structured catalytic packings for miniature methanol fuel processor: Methanol steam reforming and CO preferential oxidation

摘要

The microfibrous structured catalytic packings for miniature fuel processor consisting of a methanol steam reformer and a subsequent CO cleanup train has been investigated experimentally. A highly void and tailorable sinter-locked microfibrous carrier consisting of 3.5 vol% 8 nm diameter Ni-fibers is used to entrap 35 vol% 150-250 nm catalyst partic-ulates for both methanol steam reforming (MSR) and CO preferential oxidation (PROX). We demonstrate a microfibrous entrapped Pd-ZnO/Al_2O_3 catalyst packings for high efficiency hydrogen production by the MSR reaction. The use of microfibrous entrapment technology significantly enhances the catalyst utilization efficiency by a 4-fold improvement of the weight hourly space velocity (WHSV), compared to the single Pd-ZnO/Al_2O_3 particulates as keeping the methanol conversion at >98%. The microfibrous entrapped Pt-Co/Al_2O_3 catalyst packings can drive the CO from 2% down to <50 ppm at 150 ℃ with O_2/CO ratio of 1 using~(-1) gas hourly space velocity (GHSV) of 32,000 h ~(-1). Finally, a prototype fuel processor system integrating MSR reformer and CO PROX train is demonstrated as three reactors in series. Such test rig is capable of producing roughly 1700 standard cubic centimeter per minute (seem) PEMFC-grade H_2 (equivalent to ～163W of electric power) in a longer-term test, in which the MSR reactor is operated at 300 ℃ using~(-1) methanoVwater (1/1.1, mole) mixture WHSV of 9 h~(-1) and CO PROX reactors at 150 ℃ using~(-1)n O_2/CO molar ratio of 1.3, respectively. In the test of this prototype system, MSR reactor delivers >97% methanol conversion throughout the entire 1200-h test; the CO cleanup train placed in line after 800-h MSR illustrates the capability to decrease the CO concentration from ～3.5% to ～1% at PROX-1 and then to less than 20 ppm at PROX-2 until to the end of test.