THE EFFECT OF CATALYST PORE STRUCTURE ON LIQUID-PHASE CATALYSIS - HYDROGENATION OF STEARONITRILE OVER RUTHENIUM SUPPORTED ON MESOPOROUS SULFATED ZIRCONIA

Ruthenium supported on mesoporous sulfated zirconia was tested as a ca talyst for the liquid phase hydrogenation of stearonitrile, n-C17H35CN , and compared with Ru, supported on either microporous sulfated zirco nia or the zeolite HY. The mesoporous catalyst is significantly more a ctive than the microporous catalyst; the zeolite supported catalyst is inactive under the same conditions. The results illustrate the effect of pore size on the reaction rate for large molecules. Both mesoporou s and microporous catalysts show good stability and a high selectivity towards formation of primary amine. The reaction order in hydrogen is positive with both catalysts; the apparent reaction order in nitrile is negative with the mesoporous catalyst but positive with the micropo rous catalyst. The activation energy of the reaction is about 90 kJ/mo l. TPR data show that under the conditions chosen for pretreatment no SO4 reduction takes place; at higher temperature the sulfur is reduced from S6+ to S2-. (C) 1997 Elsevier Science B.V.