ABSTRACT
Chemical Research Center, Institute of Surface Chemistry and Catalysis, H-1025 Budapest, Pusztaszeri út 59-67, Hungary
gobolos@chemres.hu
Abstract Amination of i-butanol to diisobutylamine was investigated on vanadium modified granulated Raney® nickel catalyst in a fixed bed reactor. The addition of 0.5 wt.% V to Raney® nickel improved the yield of amines and the stability of catalyst. Factorial experimental design was used to describe the conversion of alcohol, the yield and the selectivity of secondary amine as a function of “strong” parameters, i.e. the reaction temperature, space velocity and NH3/i-butanol molar ratio. Diisobutylamine was obtained with 72% yield at 92% conversion and reaction parameters: P=13 bar, T=240°C, WHSV=1 g/g h, and molar ratios NH3/iBuOH= 1.7, H2/NH3= 1.9. Introduction Amines find application as intermediates in many fields of industry and agriculture (1). Lower alkylamines are usually produced by the amination of the corresponding alcohols with ammonia. However, only scare data are available in the literature on the preparation of isobutylamines. In the alkylation of NH3 or amines with alcohols, Co-, Ni-or Cu-containing catalysts are mainly used (1). Nickel catalysts produce mainly primary amine, however, in many applications secondary amines are needed. Diisobutylamine ((iBu)2NH) was obtained from i-butanol (iBuOH) and i-butylamine with 60% yield on 20wt.%Co-5wt.%Ni/Al2O3 catalyst at 200ºC (2). Supported nickel catalysts containing 25-45 wt.% metal were active in producing (iBu)2NH from iBuOH and NH3 with 65-72% yield at 86-92% conversion, and also at 200ºC (3). In this work the effect of process parameters on the amination of iBuOH to (iBu)2NH was studied over V-modified Raney® nickel. V is known to increase the yield of amines and the stability of catalyst (4,5). Factorial experimental design was used to describe the conversion of alcohol, and the yield and selectivity of secondary amine as a function of reaction temperature, space velocity and NH3/iBuOH molar ratio. Results and Discussion The V-modified Raney® nickel catalyst showed noticeable stability in time-onstream experiment for 55 h, and tolerated several heating-cooling cycles. It is
noteworthy that the conversion of i-butanol was ca. 86%, and yield of monosecondary and tertiary amine was ca. 18, 65 and 3%, respectively (see Figure 1). The conversion and the amine yield listed in Table 1 indicate that the H2 pressure has little effect on catalytic performance in the range investigated.
