Supported bimetallic core-shell structure catalyst and its preparation method
The purpose of the invention is to provide a supported bimetallic core-shell structure catalyst and its preparation method. Supporter, metal salt and reducing agent solution are mixed to synthesize the catalyst M@PdM/ZT by using a one-step synthesis method, wherein the active metal particle M@PdM as core-shell structure, M Is the core representing one of the Ag, Pt, Au and Ir. ZT is the supporter, representing one of hydrotalcite (Mg 2 Al-LDH), alumina (Al 2 O 3 ) and silica (SiO 2 ). By changing the temperature and the reaction time to control the kinetic behavior of the reduction of two kinds of metal ions to realize the construction of core-shell structure. Active metal particle composition and shell thickness are regulated by controlling metal ion concentration. The bimetallic core-shell catalyst prepared by this method showed excellent selectivity and stability in acetylene selective hydrogenation and anthraquinone hydrogenation.
1. A preparation method of supported bimetallic core-shell catalyst comprising:
adding M salt and Pd salt to a reducing solution to obtain a mixed salt solution after ultrasonic irradiation for 4-5 min; wherein a total concentration of M and Pd ions is 0.01-20 mmol/L, a molar ratio of M:Pd ions is 0.1 to 10; M is one of Ag, Pt, Au and Ir; M salt is one of AgNO 3 , HPtCl 6 , Pt(C 5 H 7 O 2 ) 2 , H 2 IrCl 6 .6H 2 O, Ir(C 5 H 7 O 2 ) 3 and HAuCl 4 .4H 2 O; Pd salt is one of the PdCl 2 , Pd(NO 3 ) 2 , Pd(C 5 H 7 O 2 ) 2 , Pd(CH 3 COO) 2 ; the reducing solution is a mixture of reducing agent and deionized water, wherein, a mass ratio of the deionized water is 0-20%; the reducing agent is one of ethylene glycol, isopropanol, N, n-dimethyl acetamide, N, n-dimethyl formamide and glyceraldehyde; stirring and heating the mixed salt solution for 10-30 min under 40-50° C., adding a supporter and continuing to stir for 10-20 min; raising temperature to 100-160° C. and keeping the temperature for 0.5-24 h to obtain a black precipitate suspension; dropping to room temperature to obtain gray or black powders after centrifuging, washing and drying; wherein the gray or black powders are catalyst M@PdM/ZT containing metal active ingredient particles dispersed on the supporter; the metal active ingredient particles are of a core-shell structure with M being the core and PdM alloy being the shell; the supporter is one of alumina (Al 2 O 3 ), silica (SiO 2 ) and hydrotalcite (Mg 2 Al-LDH).
2. A supported bimetallic core-shell catalyst M@PdM/ZT comprising metal active ingredient particles dispersed on a supporter, wherein the active metal ingredient particles contain M and PdM alloy and are of a core-shell structure; M is the core with a diameter of 5-15 nm, and selected from the group consisting of Ag, Pt, Au and Ir; PdM alloy is the shell with a thickness of 1-10 nm; ZT is the supporter, and selected from the group consisting of hydrotalcite (Mg 2 Al-LDH), alumina (Al 2 O 3 ) and silica (SiO 2 ).