Catalysis Letters 39 (1996) 63q55 63 Alkylation of naphthalene with alcohols over mesoporous MCM-41 Basab Chakraborty, Alex C. Pulikottil and B. Viswanathan Department of Chemistry, lndian Institute of Technology, Madras 600 036, India Received21 December 1995; accepted 16 February 1996 Mesoporous MCM-41 is found to promote alkylation of naphthalene by alcohols. In addition to the preferred branched side chain products n-alkylated product is also observed in the case ofpropylation of naphthalene. K9 MCM-41; naphthalene; alkylation; isomerization 1. Introduction Catalytic alkylation of aromatics with various alky- lating agents over zeolites has been the subject of exten- sive studies because of the shape selective features of the reaction [1-3]. However, the alkylation of polynuclear aromatics over zeolites is restricted primarily by its pore size. Alkylation ofpolynuclear aromatics with lower ole- fins, alcohols, and alkyl halides is carried out in presence of mineral acids or conventional Lewis acids, which yield non-selective product mixtures which are not environ- mentally acceptable [4]. Alkylation of naphthalene by zeolites, especially methylation, has been studied extensively [3,5-7]. Fraenkel et al. [5] have reported a higher conversion for methylation of naphthalene in vapour phase over large pore HM and HY zeolites in comparison to the medium pore HZSM-5. Katayama et al. [6] have reported liquid phase isopropylation of naphthalene over various zeo- lites. It has been observed that mordenite type zeolites show better selectivity towards alkylation by propylene and non-selective feature towards methylation, demon- strating the effectiveness of pore size in selective alkyla- tion ofpolynuclear aromatics. Recently, a family of mesoporous aluminosilicates designated as MCM-41 has been developed by Mobil [8,9]. These materials can be synthesized in a wide range of Si/A1 ratios and the pore sizes can be tuned in the range of 20-100 A. Although the catalytic activities of these materials are not well documented [10], MCM-41 can be envisaged a potential catalyst for polynuclear aromatic alkylations due to its acid characteristics and pore size distribution. Hence in this study the gas phase alkylation of naphthalene with n-propanol and n-buta- nol on HMCM-41 as catalyst is reported. 2. Experimental Aluminosilicate MCM-41 was synthesized using Ludox AS40 (colloidal silica) and aluminium sulphate as the silicon and aluminium sources respectively. Cetyltrimethylammonium bromide was employed as the template. The procedure employed for synthesis was similar to that of Beck et al. [9]. The gel composition employed for the synthesis was: 59.78SIO2 : 1.0AlzO3 : 15.59TEABr : 16.20CTABr : 5.25Na20 : 2810H20. The HMCM-41 was obtained by ion exchange with 1 M ammonium chloride at 333 K for 6 h to achieve the maximum degree of exchange. The samples were then fil- tered and washed free of chloride and dried at 383 K. The H form of MCM-41 was then obtained by calcining the NH+MCM-41 at 823 K for 6 h. The Y zeolite (SIO2/A1203 = 4.9) and ZSM-5 (SiO2/ A1203 = 60) were prepared using standard methods. The H forms of the Y and ZSM-5 were obtained by a method analogous to the method employed for MCM- 41. Surface area measurements were carried out by nitro- gen adsorption at 77 K on a Carlo Erba sorptometer (1800). The XRD patterns were recorded with a Rigaku Miniflex powder diffractometer using Cu Ks radiation. Catalytic reactions were carried out in a continuous flow reactor. The products were separated and analyzed using a GC MS (Shimadzu model QP1000EX) equipped >= \ - :-~ = : ~ ( b ) Degrer 2 e Fig. 1. XRD pattern of(a) calcined MCM-41, (b) HMCM-41. 9J.C. Baltzer AG, Science Publishers