Abstract
Continuous hydrogenation of dimethyl maleate (DMM) toγ-butyrolactone (GBL), 1,4-butanediol (BDO) and tetrahydrofuran (THF) is a promising process in industry. In this study, Cu-M/SiO2 catalysts modified by basic promoters (M = Mg, Ca, Sr, Ba, La) were prepared, and characterized by physical adsorption of N2, in situ XRD, H2-TPR, CO2-TPD. With the addition of basic promoters, the basicity of Cu-M/SiO2 catalysts was improved. The particle size of CuO on Cu-M/SiO2 catalyst was increased after modified by Mg, Ca, Sr, Ba. However, the CuO particle was decreased on the Cu-La/SiO2 catalyst. The series of Cu-M/SiO2 catalyst was applied to the hydrogenation of DMM. The addition of basic promoters increased the selectivity of GBL during the hydrogenation for the basic promoters improved the dehydrogenation of BDO to GBL in alkaline sites. Furthermore, Cu-La/SiO2 presented a higher activity in the hydrogenation of DMM, due to its higher dispersion of Cu.
Highlights
Catalysts Characterization25 wt% Cu/SiO2 and 25 wt% Cu-5 wt% M/SiO2 were characterized by N2 physical adsorption, in situ XRD, H2 temperature-programed reduction (H2-TPR) and CO2 temperature-programed desorption (CO2-TPD)
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DWMithMthaes fsrheoqwuenntinbrSecahketmhreou1)gh[4o–7f ]t.hWe oitxhidtahteiofnretqeuchenntolborgeyakotfhnro-buugthanoef ttohemoaxliedicatainohnytdecrihdneoalongdythoef nd-ebcuretaanseeotfopmroadleuicctiaonnhcyodsrti,ditewanildl btehoefdseigcnreifiasceanocfepfroordthuectdioenvecloosptm, ietnwt iollf tbheeodfoswignnsitfriecaamncperfoodrutchtes dofevmealolepimc aennht yodfrtihdee.dEoswtenrsifitrceaatmionporof dmuacltesicoafnmhyalderiicdaenahnyddmrideteh. aEnsotelrtiofiDcaMtioMn, oafndmtahleeinc caonnhtyinduroidues ahnyddrmogeethnaantioolntotoDBMDMO, GanBdL tahnedn TcoHnFt,inarueocuosnhsyidderroegdentoatbioena tvoerByDpOr,oGmBisLinagntdecThHnFo,loagrey.cTohnesikdeeyretdo ttohibseparovceersys pisrothmeisciantaglytescthfnoor lhoygdyr.oTgheenkateiyontootfhDisMpMro.cess is the catalyst for hydrogenation of ddiimmeetthhyyll mmaaleate (DMM)
Summary
25 wt% Cu/SiO2 and 25 wt% Cu-5 wt% M/SiO2 were characterized by N2 physical adsorption, in situ XRD, H2-TPR and CO2-TPD. The conversion rate of DMM reached 100% over the unmodified Cu/SiO2 catalyst showed its good activity, and THF as the only hydrogenated product was observed for the weak alkalinity of the Cu/SiO2 surface. After the basic additive (except La) was added to Cu/SiO2 catalyst, the catalytic activity decreased significantly for the conversion of DMM over Cu-M/SiO2 (M = Mg, Ca, Sr, Ba) did not reach 100%, especially the conversion over Cu-Ba/SiO2 just 64.21%. The addition of basic promoter to Cu/SiO2 catalyst varied the selectivity of the hydrogenation products. One possible reason for the low selectivity of THF over modified catalysts was the covering of the part of the acid sites on the surface of SiO2 by the basic additives leading to the weakening of the dehydration of BDO to THF under acidic conditions.
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