Hel­mut Knözinger passed away at his home in Munich on Jan­u­ary 12, 2014, at age 78. The catal­y­sis com­mu­ni­ty los­es an active mem­ber of many years, a con­trib­u­tor of out­stand­ing sci­ence, leader in var­i­ous orga­ni­za­tions, edi­tor of key pub­li­ca­tions, and part­ner in vibrant collaborations.

Knözinger stud­ied Physics at Lud­wig-Max­i­m­il­ians-Uni­ver­sität München, with Phys­i­cal Chem­istry becom­ing his area of empha­sis dur­ing his time as a doc­tor­al stu­dent. His dis­ser­ta­tion (1961), which was super­vised by Georg-Maria Schwab, was his entrance into the field of catal­y­sis; he inves­ti­gat­ed the suit­abil­i­ty of the cat­alyt­ic decom­po­si­tion of methyl for­mate as a test reac­tion. He con­tin­ued on with the Habil­i­ta­tion (1967), the qual­i­fi­ca­tion for pro­fes­sor­ship with­in the Ger­man aca­d­e­m­ic sys­tem (Doc­tor of Sci­ences in oth­ers). The top­ic of the asso­ci­at­ed the­sis was the dehy­dra­tion of ethanol on alu­mi­na, a mate­r­i­al that would lat­er be the sub­ject of his per­haps most famous arti­cle. Knözinger held var­i­ous aca­d­e­m­ic posi­tions at Lud­wig-Max­i­m­il­ians-Uni­ver­sität München, with an inter­lude as a guest pro­fes­sor at the Uni­ver­si­dad Cen­tral de Cara­cas, Venezuela (1968/69), before he arrived at his final rank of pro­fes­sor (1980). He remained true to his alma mater until his offi­cial retire­ment in 2000, after which he kept an office and con­tin­ued to be active as a researcher and editor.

Knözinger researched in many dif­fer­ent areas of catal­y­sis and excelled at devel­op­ing and apply­ing spec­tro­scop­ic meth­ods for the char­ac­ter­i­za­tion of cat­a­lysts. Each of the class­es of mate­ri­als in his focus can be asso­ci­at­ed with meth­ods that he tai­lored for the pur­pose of their inves­ti­ga­tion. He made sig­nif­i­cant con­tri­bu­tions to the char­ac­ter­i­za­tion of acid-base prop­er­ties of oxid­ic mate­ri­als, ana­lyz­ing the OH groups spec­tro­scop­i­cal­ly, and exten­sive­ly using car­bon monox­ide (CO) as a probe but also explor­ing much sought-for probe mol­e­cules for basic sur­face prop­er­ties. This work is doc­u­ment­ed in many orig­i­nal and review arti­cles, includ­ing those on alu­mi­na in Catal­y­sis Reviews-Sci­ence and Engi­neer­ing in (with Rat­nasamy, 1978), on CO adsorp­tion in Mate­ri­als Chem­istry and Physics (with Zaki, 1987), on weak­ly inter­act­ing probes for zeo­lites in Jour­nal of the Chem­i­cal Soci­ety — Fara­day Trans­ac­tions (with Huber, 1998), and on acid-base char­ac­ter­i­za­tion in the Hand­book of Het­ero­ge­neous Catal­y­sis (2008). Relat­ing to his work on CO as a probe mol­e­cule, he also applied his skill in infrared spec­troscopy to sup­port­ed car­bonyl com­plex­es, of which he wrote in Ange­wandte Chemie Inter­na­tion­al Edi­tion (with Lamb and Gates, 1988). Oxides sup­port­ed on oth­er oxides was anoth­er focus area, with appli­ca­tions of the cat­a­lysts for exam­ple in hydrodesul­fu­r­iza­tion and selec­tive cat­alyt­ic reduc­tion. In addi­tion to probe mol­e­cule adsorp­tion and IR spec­troscopy — his forte, he applied Raman, UV-vis, and pho­to­elec­tron spec­troscopy. To inves­ti­gate the mech­a­nism of dis­per­sion of oxides on oth­er oxides, exper­i­ments to observe the trans­port were designed, and in a long-last­ing col­lab­o­ra­tion with the Insti­tute for Plas­ma Physics in Garch­ing (a Max-Planck Insti­tute), thin film mod­el cat­a­lysts were inves­ti­gat­ed by sur­face sci­ence tech­niques such as ion scat­ter­ing and Auger elec­tron spec­troscopy. Exam­ples of this work are the arti­cles on molyb­de­na sup­port­ed on alu­mi­na in Jour­nal of Phys­i­cal Chem­istry (with Jeziorows­ki, 1978) or on sol­id-sol­id wet­ting in Sur­face Sci­ence in (with Leyr­er, Mar­graf, and Taglauer, 1988).

Knözinger’s work was rec­og­nized with nation­al and inter­na­tion­al awards, among them the Cia­pet­ta Lec­ture­ship (1980), the Ipati­eff Lec­ture­ship (1988), the Max-Planck Research Award (1995), the Prix Gay Lus­sac Hum­boldt Prize (1997), and the Alwin Mit­tasch Medal of Dechema (1998). He became an hon­orary mem­ber of the Hun­gar­i­an Acad­e­my of Sci­ences in (1995), a mem­ber of the Acad­e­mia Europaea (2000), and an hon­orary pro­fes­sor of Nankai Uni­ver­si­ty, Tian­jin, Chi­na (2004). He was a mem­ber of chem­i­cal and catal­y­sis soci­eties, and helped orga­nize nation­al and inter­na­tion­al con­fer­ences on catal­y­sis. Notably, he was first a mem­ber of the Euro­pean Asso­ci­a­tion of Catal­y­sis and then lat­er the rep­re­sen­ta­tive of the Fed­er­al Repub­lic of Ger­many in the Coun­cil of the Euro­pean Fed­er­a­tion of Catal­y­sis Soci­eties (1993–1999). He also act­ed as pres­i­dent of the Inter­na­tion­al Asso­ci­a­tion of Catal­y­sis Soci­eties (1996–2000).

As edi­tor, Knözinger moved into the foot­steps of Schwab, who had edit­ed a hand­book of catal­y­sis. Togeth­er with Ertl and Weitkamp, Knözinger pub­lished the first edi­tion of the Hand­book of Het­ero­ge­neous Catal­y­sis with five vol­umes in 1997. Such was the suc­cess that a sec­ond edi­tion, with Schüth as addi­tion­al edi­tor and eight vol­umes, appeared in 2008. He served as an edi­tor of Advances in Catal­y­sis, in the years 1998 through 2011; under his reign, three vol­umes were ded­i­cat­ed to spec­tro­scop­ic analy­sis of the work­ing catalyst. 

While Knözinger remained root­ed in Munich through­out his career, he cul­ti­vat­ed col­lab­o­ra­tions and exchange. He him­self was an avid trav­el­er and also a guest pro­fes­sor mul­ti­ple times, in Cara­cas, Xian­men, Evanston, Ams­ter­dam, and Paris. Researchers from around the world vis­it­ed his lab­o­ra­to­ry (their prove­nience was, in fact, tracked by pins in a wall map at the insti­tute), most­ly to per­form IR spec­tro­scop­ic exper­i­ments using his spe­cial­ly designed appa­ra­tus. Guests were treat­ed with gra­cious­ness and enjoyed Bavar­i­an hospitality. 

His con­stant inter­est in everybody’s research was man­i­fest in his dai­ly after­noon rounds through the labs with indi­vid­ual con­ver­sa­tions, his recep­tion of a knock at his office door, his overnight read­ing of man­u­scripts hand­ed to him. His reli­a­bil­i­ty and his self-dis­ci­pline were exem­plary. His advis­ing was nev­er force­ful, pro­mot­ing aca­d­e­m­ic free­dom and inde­pen­dence. A sig­nif­i­cant num­ber of stu­dents achieved the doc­tor­al degree under his guid­ance and are tes­ta­ment to his skill as an advi­sor and men­tor. Knözinger was a gift­ed ath­lete in his youth and a moun­tain enthu­si­ast; he insti­gat­ed reg­u­lar group out­ings – hik­ing in sum­mer and ski­ing in win­ter. He cre­at­ed an atmos­phere of togeth­er­ness that let team spir­it and humor flour­ish and friend­ships be forged.

Knözinger was also a tal­ent­ed pho­tog­ra­ph­er and adhered to this pas­sion through­out his life – his cam­era accom­pa­nied him on most occa­sions. The var­i­ous pho­tographs dis­played in his office spoke of his skill, of his trav­els around the world, and his eye as an observer. 

Hel­mut Knözinger’s pres­ence and his views will be missed.
 
Friederike Jentoft