CATALYSTS FOR HIGH CETANE ETHERS AS DIESEL FUELS

摘要: A tungstena-zirconia (WZ) catalyst has been investigated for coupling methanol and isobutanol to unsymmetrical ethers, i.e. methyl isobutyl ether (MIBE) compared with earlier studied sulfated-zirconia (SZ) Nafion-H catalysts. In all cases, the synthesis mechanism is a dual site S{sub N}2 process involving competitive adsorption of reactants on proximal acid sites. At low reaction temperatures, methylisobutylether predominant product. However, at temperatures >135 C WZ very good dehydration isobutene. The surface sites were diagnosed by high resolution X-ray photoelectron spectroscopy (XPS) N 1s shifts after amines. Using pyridine, ethylenediamine, triethylamine, it shown that heterogeneous strong Broensted Theoretical study located transition state alcohol accounted well XPS core-level upon acid-base interactions. While computations have not carried out WZ, SZ slightly stronger than CF{sub 3}SO{sub 3}H (a model Nafion-H) 1.3-1.4 kcal/mol. novel sulfated zirconia having was synthesized significantly enhanced activity selectivity in producing MIBE or isobutene from methanol/isobutanol mixtures. prepared anchoring 1,2-ethanediol bis(hydrogen sulfate) salt precursor onto zirconium hydroxide, followed calcination remove -(CH{sub 2}CH{sub 2})- bridging residues.