Kenzi Tamaru — A “titan of mechanism” who initiated the in-situ study of catalysts

 
On July 22, 2020, the sci­en­tif­ic com­mu­ni­ty lost Ken­zi Tamaru, a pio­neer in elu­ci­dat­ing the mech­a­nisms of het­ero­ge­neous cat­alyt­ic reac­tions. His endur­ing lega­cy will be his insight that cat­a­lysts have to be stud­ied at reac­tion con­di­tions. This insight was the basis for the now wide­spread use of in situ and operan­do stud­ies in catal­y­sis.

Ken­zi Tamaru was born in Kamaku­ra, Japan on Nov. 2, 1923, and was edu­cat­ed at the Uni­ver­si­ty of Tokyo, obtain­ing his B.S. in 1946, and his Ph.D. in 1950. In 1953 he was award­ed a Full­bright Fel­low­ship and went to work with Sir Hugh Tay­lor at Prince­ton Uni­ver­si­ty where he stayed until 1956. In Prince­ton Ken­zi stud­ied the decom­po­si­tion of ger­mane and got the insight of the need to study cat­a­lysts at reac­tion con­di­tions. When he told Prof. Tay­lor of this con­cept he said “You are very ambi­tious”, repeat­ing it, “You are very ambi­tious”. On return­ing to Japan, Ken­zi start­ed research on adsorp­tion dur­ing catal­y­sis, first at Yoko­hama Nation­al Uni­ver­si­ty, and then at the Uni­ver­si­ty of Tokyo. In Adv. Catal. 15 (1965) 65–90, he stat­ed “The state of the sur­face which cat­alyzes reac­tions is not that of the sur­face in the absence of reac­tants. The prop­er­ties of a cat­a­lyst sur­face to be stud­ied should be those in the work­ing state.” Today, the need to study cat­a­lysts at in situ con­di­tions is uni­ver­sal­ly rec­og­nized and is applied reg­u­lar­ly using spec­tro­scop­ic and tran­sient tech­niques. Ken­zi Tamaru liked to tell his stu­dents, “You have a good head, so think care­ful­ly”. This think­ing was evi­dent in him at an ear­ly stage. His grade school teacher recalled that when stu­dents were asked to name some­thing that would not burn most stu­dents answered with things like stones or steel. Kenzi’s unique answer was “ash­es”. Ken­zi Tamaru’s appli­ca­tion of what he liked to call “the Tamaru Method”, includ­ed in situ stud­ies of MeOH decom­po­si­tion on ZnO and Cr₂O3, NH₃ decom­po­si­tion on W and Mo, and CO hydro­gena­tion on Ru, and the phe­nom­e­non of adsorp­tion-assist­ed des­orp­tion. Ken­zi had close friend­ships with many dis­tin­guished indi­vid­u­als in the field, notably Michel Boudart, Wolf­gang Sachtler, and Guo Xiex­i­an, with whom he shared a com­mon inter­est in chem­i­cal kinet­ics as well as per­son­al rela­tions. Ken­zi Tamaru held many impor­tant posi­tions includ­ing the pres­i­den­cies of the Japan Chem­i­cal Soci­ety in 1989–1990, and the Inter­na­tion­al Asso­ci­a­tion of Catal­y­sis Soci­eties in 1988–1992. He was rec­og­nized with many awards, includ­ing the Japan Chem­i­cal Soci­ety Award in 1974, the Pur­ple Agate in 1985, and the Japan Acad­e­my Award in 2000.

His pres­ence will be missed but his con­tri­bu­tions will endure.