EFFECT OF PD BLACK DEPOSITS ON SUCCESSIVE HYDROGENATION OF 4-METHYLSTYRENE WITH ACTIVE HYDROGEN PASSING THROUGH A PD SHEET ELECTRODE

A Pd sheet electrode was chemically palladinized with active hydrogen passing through it. The Pd black deposits grew up three-dimensionally with increasing palladinization time, causing the marked increase in r eaction zone or number of reaction site for the hydrogenation. The rat e of 4-ethyltoluene production (v) in the hydrogenation of 4-methylsty rene at the palladinized Pd sheet electrodes increased over 40 times l arger than that: at the Pd sheet electrode without palladinization. In addition, the reciprocal of the v value linearly depended on the reci procal of surface roughness factor, supporting the idea that the rate- determining step changed from the hydrogenation to the supply of the a ctive hydrogen together with the increase in surface roughness factor of the palladinized Pd sheet electrode.