Catalysis of Organic..

Gelder, Jackson and Lok 175measured using CO chemisorption. Taking a CO: Pd ratio of 1:2 the dispersionwas calculated as 42.0 % and an approximate metal particle size determined as2.6 nm.Hydrogenation was carried out in a Buchi stirred autoclave. The catalyst(0.1 g) was added to the reactor with the reaction solvent (280 mL methanol)and reduced in a flow of hydrogen (30 cm 3 min -1 ) for 30 minutes with a stirringrate of 300 rpm. During reduction the reactor temperature was increased to 323K. The reactant, nitrobenzene (8.5 mL, 0.08 mol), nitrosobenzene (8.85 g, 0.08mol) or azobenzene (7.5 g, 0.04 mol) was then added and the hydrogen pressureset at 2 barg and the stirrer speed at 1000 rpm. In reactions involving theaddition of one of the intermediates along with nitrobenzene, the intermediatewas added first and mixed with the solvent under nitrogen before nitrobenzenewas added and reaction commenced. No variation in hydrogenation rate wasobserved over a range of stirrer speeds (800 – 1500 rpm) indicating the absenceof mass transfer control. Analysis of the reaction mixture was performed byGC-MS using a Varian CP-3800 GC with a Varian Saturn 2000 Trace MSdetector fitted with a 25 m DB-5 column. The rate of hydrogenation wasmeasured using the gas flow controller fitted to the autoclave and the rate ofaniline production was calculated using the GC-MS data.AcknowledgementsThe authors would like to thank EPSRC and Johnson Matthey for fundingthis project and Dr. T. A. Johnson for his helpful suggestions.Acknowledgment is made to the Donors of The American Chemical SocietyPetroleum Research Fund, for the support of this work through the awardof a travel grant.References1. K. Weissermel and H.-J Arpe, Industrial Organic Chemistry, 3 rd ed. VCH,Weinheim, p. 377 19972. A. Metcalfe, M. W. Rowden, J. Catal., 22, 30 (1971)3. D. J. Ostgard, M. Berweiler, S. Roder, K. Mobus, A. Freund and P. Panster,Chemical Industries (Dekker), 82, (Catal. Org. React.), 75 (2001).4. X. Yu, M. Wang, H. Li, Appl.Catal. A, 202, 71 (2000)5. S. R. de Miguel, J. I. Vilella, E. L. Jablonski, O. A. Scelza, C. Salinas-Martinez de Lecea, A. Linares-Solano, Appl. Catal. A, 232, 237 (2002)6. F. Haber, Zeit. Electrochem., 4, 506 (1898)7. H. D. Burge, D. J. Collins, Ind. Eng. Chem. Prod. Res. Dev., 19, 389 (1980)8. V. Höller, D. Wegricht, I. Yuranov, L. Kiwi-Minsker, A. Renken, Chem.Eng. Technol., 23, 251 (2000)9. F. Figeras, B. Coq, J. Mol. Catal. A., 173, 223 (2001)