Development of advanced catalysts using fine particles of intermetallic compounds.

制备了负载型和非负载型金属间化合物Ni_3Ge、Pd_3Bi、Pt_3Sn、PtCu和Pt_3Co，并用XRD对其进行了表征，确定了它们的晶相和晶粒尺寸。测定了IMC的程序升温还原以确定合适的还原温度。吸附CO的红外光谱表明，在Ni_3Ge的情况下发生了电子从Ni向Ge的转移，在Pd_3Bi的情况下发生了电子从Bi向Pd的转移。在H_2-D_2平衡反应中，只有Ni_3Ge具有与Ni相当的活性，其它IMCs的活性均远低于Pd和Pt。Ni_3Ge/SiO_2和Pd_3Bi/SiO_2对部分加氢制乙烯具有高选择性。结果表明，该催化剂对乙烯的选择性和稳定性均高于商品Pd-Ag/SiO_2催化剂。两种IMC催化剂对过量乙烯中少量乙炔的选择性加氢也具有活性和选择性。Pt_3Sn/H-SAP 0 - 11催化剂在丁烷脱氢异构化反应中表现出较高的异丁烯选择性。研究了Pt-IMCs在氢气中CO选择氧化反应中的催化性能。PtCu/SiO_2和Pt_3Co/SiO_2在低温下的催化活性远高于Pt/SiO_2。水的加入加快了PtCu/SiO_2催化剂的氧化速率。结果表明，在Pt_3Co/SiO_2催化剂中，氢氧化生成的水分子加速了氧分子在表面的吸附，促进了CO的氧化;在Pt_3Co/SiO_2催化剂中，氧分子在Co原子上发生解离吸附，促进了CO的低温氧化。

Supported and unsupported intermetallic compounds (IMCs), Ni_3Ge, Pd_3Bi, Pt_3Sn, PtCu and Pt_3Co, were prepared and characterized by XRD to identify their crystal phases and obtain the size of their crystallites. Temperature programmed reduction of IMCs was measured to determine the appropriate temperature of reduction. IR spectra of adsorbed CO indicated the electron transfer from Ni to Ge in the case of Ni_3Ge and from Bi to Pd in the case of Pd_3Bi. The catalytic activity for H_2-D_2 equilibration was measured and it was revealed that only Ni_3Ge showed comparable activity to Ni and that the other IMCs showed much lower activity than Pd and Pt.Silica supported IMCs were used for the catalyst in acetylene hydrogenation with a continuous flow reaction system. Ni_3Ge/SiO_2 and Pd_3Bi/SiO_2 gave high selectivity for the partial hydrogenation into ethylene. The latter was found to have higher selectivity and stability for ethylene formation than commercial Pd-Ag/SiO_2. Both IMC catalysts were also active and selective for the selective hydrogenation of a small amount of acetylene in excess ethylene. Pt_3Sn/H-SAP0-11 showed high selectivity to isobutene in the dehydroisomerization of butane. The catalytic properties for the preferential oxidation of CO in hydrogen was studied for Pt-IMCs. PtCu/SiO_2 and Pt_3Co/SiO_2 showed much higher activity than Pt/SiO_2 at low temperatures. The addition of water in the feed accelerated the rate of oxidation on PtCu/SiO_2. It was revealed that water molecules produced through the oxidation of hydrogen accelerate the adsorption of oxygen molecules on the surface to promote the oxidation of CO. In the case of Pt_3Co/SiO_2, the dissociative adsorption of 02 takes place on Co atoms to accelerate the oxidation of CO at low temperatures.