tailieunhanh - Conversion of styrene into benzaldehyde and styrene epoxide over MgCoAl-LDH catalysts

The catalysts exhibited a very high activity in the conversion of styrene into two main products (benzaldehyde and styrene oxide). The highest styrene conversion was about 90 – 95 % and the total selectivity to benzaldehyde and styrene oxide was in the range of 80 – 85 % under reported experimental conditions. | Vietnam Journal of Science and Technology 55 (4) (2017) 403-410 DOI: CONVERSION OF STYRENE INTO BENZALDEHYDE AND STYRENE EPOXIDE OVER MgCoAl-LDH CATALYSTS Nguyen Tien Thao*, Dang Van Long, Dinh Minh Hoan Faculty of Chemistry, VNU University of Science, Vietnam National University Hanoi, 19 Le Thanh Tong ST, Hoan Kiem, Hanoi, 10000, VIETNAM * Email: ntthao@, nguyentienthao@ Received: 13 July 2016; Accepted for publication: 13 March 2017 ABSTRACT Co-containing hydroxides have been successfully synthesized by the co-precipitation of starting-metal salts. The obtained materials were characterized by some physical means including XRD, EDS, nitrogen physisorption, etc. It was found that Co2+ ions were present in the layered double hydroxide (LDH) sheets. The presence of cobalt ions in LDH played as active sites for the oxidation of styrene with air. The catalysts exhibited a very high activity in the conversion of styrene into two main products (benzaldehyde and styrene oxide). The highest styrene conversion was about 90 – 95 % and the total selectivity to benzaldehyde and styrene oxide was in the range of 80 – 85 % under reported experimental conditions. Keywords: styrene, benzaldehyde, epoxide, LDH, hydrotalcite. 1. INTRODUCTION The catalytic oxidation of alkenes of great interest since the oxygenated compounds are the most useful synthetic intermediates for a wide variety of products such as pharmaceuticals, polymers, and epoxy paints [1]. For example, benzaldehyde is widely used in many industrial fields like pharmaceuticals, dyes, resin additives, flavors which always required a high purity in order to use in food or medical industries. Nowadays, in the advanced process of styrene oxidation, benzaldehyde requires to produce as an main by-product without halogen and thus has a wider application [1, 2]. Meantime, the conventional methods for the oxidation of unsaturated hydrocarbons in industry are known as the .