Preparation And Study Of Copper-based Catalyst For Slurry Methanol Synthesis

The liquid-phase methanol synthesis process has many advantages such as high reaction heat transfer rates, suitable for CO-rich syngas, high conversion per pass, no or less circulation of tail gas, replacement of catalyst on-line, flexible on operational load, etc., are suitable for large-scale production of methanol and especially for being involved in the coal-based integrated gasification combined cycle. But the catalyst used was mostly the crashed commercial CuO/ZnO/Al2O3 catalyst for fixed-bed methanol synthesis process, and has not been commercially popularized until now, because of its poor stability.(1) In preparation of CuO/ZnO/Al2O3 catalyst precursors by traditional co-precipitation, microwave irradiation promoted the selectivity of phase in precursor. Thus, precursor possessed more (Cu, Zn)5(CO3)2(OH)6 and its crystal degree became stronger. When the ratio of Cu to Zn was 2.0, it exhibited well synergy, well dispersion after calcination, which benefited to slurry methanol synthesis and excelled the catalytic performance of catalyst prepared by water heating.(2) In preparation of CuO/ZnO/Al2O3 catalyst precursors by traditional co-precipitation, suspension was prepared by precipitating aluminum first, copper and zinc were precipitated in the obtained suspension. Cu2CO3(OH)2 and Zn5(CO3)2(OH)6 formed and then (Cu, Zn)5(CO3)2(OH)6 and (Cu, Zn)2CO3(OH)2 after isomorphous substitution in mother liquid. copper and zinc precipitated on to aluminum simultaneously and uniformly, thus, CuO scattered evenly on carrier Al2O3, which benefited to improve catalytic performance for slurry methanol synthesis.(3) Catalyst with Zr possessed more (Cu,Zn)5(CO3)2(OH)6 in its precursor, it exhibited well synergy, small CuO crystal particle, big adsoption of CO after calcinations, it also indicated that Zr promoted reduction and dispersion of catalyst which benefits to slurry methanol synthesis. In contrast to CuO/ZnO/Al2O3 catalyst, the space time yield (STY) of catalyst with Zr precipitated at 80℃raised by 8.67%, its deactivation rate declined by 65.12%.(4) In preparation of oxalate precursors of CuO/ZnO/Al2O3 catalysts by co-precipitation, ethanol solvent selected crystal phase in generation process of precursor and restricted its growth. Microwave irradiation promoted the isomorphous substitution between oxalate copper and oxalate zinc, making the precursor mainly contain (Cu, Zn)C2O4 and exhibit nano-fibriform. Either using ethanol as solvent or adopting microwave irradiation as aging heating manner benefited slurry methanol synthesis by CO2+H2, the maximum STY reached 202.0 g·Kg-1·h-1, the conversion rate of CO2 achieved 22.65%.