Preparation Of Solid Alkali And Study On Catalytic Performance Of Ethanol

Solid strong bases have attracted widespread attention owing to its environmentally benign and economical catalytic processes, since they can catalyze a range of reactions under mild conditions and reduce waste production.The first part of this paper described the preparation of mesoporous magnesium aluminum oxide with CTAB（cetyltrimethylammonium bromide） as template, tartaric acid as complexing agent, ammonia as the precipitating agent from magnesium and aluminum salts. Four kinds of magnesium aluminum oxides were prepared with different Mg/Al molar ratio. These samples were characterized by X-ray diffraction（XRD）, thermo gravimetric and Fourier transform infrared（FTIR）, nitrogen adsorption desorption isotherms, CO₂ and NH₃ temperature programmed desorption（TPD）. The tartaric acid can reduces the crystal size of obtained magnesium aluminum oxide which assembles into mesoporous structure. The magnesium aluminum oxide exhibits high surface areas(160 m²g^-1) and pore volume(0.6 cm³g^-1). The catalytic properties to the butanol from ethanol were performed on the fixed bed reactor with on-line gas chromatography to monitor products. The conversion of ethanol reached 64.0% and the selectivity of butanol reached 78.0%.In the second part, boehmite Al₂O₃·nH₂O（n=0.08-0.62）, citric acid, CTAB and alkali（alkaline earth） metal nitrate were mixed and extruded into strips. And then the alkali（alkaline earth） metal oxide doped mesoporous aluminas were obtained after calcination. This one-step method for the synthesis of shaped solid base is more suitable for industry application. Four kinds of metal oxides（K、Ca、Na、Mg） were surveyed and the K and Ca doped aluminas exhibited high ethanol conversion and butanol selectivity.In the third part, mesoporous magnesias are prepared using magnesium nitrate as source of magnesium, urea or ammonia as precipitating agents, sodium tartrate（ST） and cetyltrimethylammonium bromide（CTAB） as co-templates. The structures and morphology of obtained mesoporous magnesias are characterized by XRD, nitrogen adsorption–desorption isotherms analysis, and scanning electron micrographs（SEM）, transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FT-IR）. The results show that the mesoporous structure of the MgO is controlled by the size of obtained MgO nanoparticle, and the size of the MgO particle can be reduced by the addition of the sodium tartrate. When urea was used as precipitation agent, the size of the MgO particle is about 20 nm, and the resulted mesoporous magnesia owned 10 nm pore with high surface area 131m²Â·g^-1; While ammonia was used as the precipitating agent, the particle size, pore diameter and surface area of the resulted mesoporous MgO were 40 nm, 38 nm and 101m²Â·g^-1 respectively.