Promoting effect of gold on the structure and activity of Co/kaolin catalyst for the 2,3-dihydrofuran synthesis L. Leite a, * , V. Stonkus a , L. Ilieva b , L. Plyasova c , T. Tabakova b , D. Andreeva b , E. Lukevics a a Latvian Institute of Organic Synthesis, 21 Aizkraukles Str., Riga LV-1006, Latvia b Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofija, Bulgaria c Boreskov Institute of Catalysis, Russian Academy of Sciences Siberian Division, 5 Acad. Lavrentjev Str., Novosibirsk, 630090, Russia Received 30 November 2001; received in revised form 7 June 2002; accepted 7 June 2002 Abstract The promoting effect of gold and the influence of the thermal pretreatment of the cobalt/kaolin catalysts on the reducibility, catalytic activity and selectivity has been studied. The catalytic properties were tested in the cyclodehy- dration of 1,4-butanediol. The gold-promoted catalysts are more selective than their non-promoted analogues. The modification by gold leads to the formation of new cobalt species, being reducible at significantly lower temperatures in comparison to those of the non-promoted catalysts. This effect of gold results not only on the dispersion, but also on the structure of the metallic cobalt phases. Ó 2002 Published by Elsevier Science B.V. Keywords: Cobalt catalyst; Gold promotion; 1,4-butanediol; 2,3-dihydrofuran; Cyclodehydration; TPR; XRD 1. Introduction Transformation of open-chain diols containing primary and secondary OH groups in the presence of catalytic quantities of metal catalysts gives commodity chemicals of a considerable industrial importance and still remains subject of the inves- tigations of different researchers. For example, 1,4- butanediol conversion into 2,3-dihydrofuran in the presence of cobalt supported catalyst is one of technological steps in the production of effective antitumor drugs [1]. The knowledge relating to catalytic diol con- versions was reviewed in [2]. The activity of Co/ kieselgur [3], Cu, Cu/Al, Cu=SiO 2 [4], Cu/kieselgur [5], Pt/C, Pt/T [6] as catalysts of diol transforma- tion has been studied. Co/kieselgur was the most selective catalyst for 2,3-dihydrofuran preparation from 1,4-butanediol with 81% yield. Particularly wide investigations in this field, including examination of the catalysts and reac- tion mechanism, were made by M. Bart ok and  A. Moln ar [2]. They studied stereochemistry and mechanism of diols dehydration and dehydro- genation on various Cu and Pt catalysts. The Catalysis Communications 3 (2002) 341–347 www.elsevier.com/locate/catcom * Corresponding author: Tel.: +371-7551822; fax: +371-7- 821038. E-mail address: leite@osi.lv (L. Leite). 1566-7367/02/$ - see front matter Ó 2002 Published by Elsevier Science B.V. PII:S1566-7367(02)00139-5