High-selectivity catalyst for production of high-quality gasoline fractions from syngas and its preparation method

A preparation method of a high-selectivity catalyst used for synthesis of high-quality gasoline fractions from syngas via Fischer-Tropsch synthesis, and is consisting of cobalt, a promoter and a molecular sieve, wherein the cobalt is presented in an amount of 1-30%, the promoter is presented in an amount of 0.01-5% and the balance is the molecular sieve based on the weight of the catalyst,

• wherein the method comprises steps of:
• (1) weighing a cobalt salt according to the content of the cobalt in the catalyst, admixing with a solvent of de-ionized water, an alcohol or a ketone to prepare a 0.5-20 wt % of cobalt salt solution;
• (2) weighing the promoter according to the content thereof in the catalyst, adding into the prepared cobalt salt solution and stirring for 0.5-3 hours;
• (3) weighing the molecular sieve according to the content thereof in the catalyst, adding the molecular sieve into the prepared cobalt salt solution, stirring for 0.1-15 hours and standing still for 0.1-24 hours;
• (4) evaporating the solid-liquid mixture at 40-100° C. and drying the solid at 30-100° C. in vacuum for 1-24 hours;
• (5) calcining the dried solid powder at 300-550° C. for 2-10 hours in the air;
• (6) shaping the calcined powder as a precursor of the catalyst;
• and
• (7) subjecting the precursor of the catalyst to reduction at 300-550° C. for 1-10 hours in an atmosphere of hydrogen or hydrogen-inert gas,
• wherein the molecular sieve is one or more selected from the group consisting of Beta, ZSM-5, MOR, Y and MCM-22, and the molecular sieve is treated by a basic solution by the following steps in sequence:
• (1) preparing a basic solution with a concentration from 0.005 mol L−1 to saturation, which is formed by dissolving one or more of nitrate, nitrite, carbonate, bicarbonate, chloride, oxalate, acetate, citrate, hydroxide and oxide of an alkali or an alkaline-earth metal in water;
• (2) mixing the molecular sieve and the basic solution according to a ratio of the bulk volume of the molecular sieve to the volume of the basic solution to be 0.2-20, and stirring for 0.1-5 hours at a temperature ranging from room temperature to 150° C. to obtain a mixture;
• (3) filtering the obtained mixture and rinsing with de-ionized water until the concentration of the alkali or alkaline earth metal ion is not higher than 1 wt % in the filtrate, sufficiently drying the filtered cake until physically adsorbed water content is within 5% by weight of the filtered cake and then obtaining a molecular sieve;
• and
• (4) adding the obtained molecular sieve into 0.05-3.0 mol of an ammonium solution, wherein the ammonium is one or more of NH4NO3, NH4Cl, (NH4)2CO3, NH4HCO3 and CH3COONH4, stirring the mixture for 0.1-3 hours at 30-100° C., filtering and rinsing the mixture with de-ionized water until the concentration of ammonium and anions is not higher than 100 ppm in the filtrate, then drying the filtered cake at 80-120° C. for 5-20 hours and calcining at 400-600° C. for 3-10 hours in the air to get the molecular sieve after treatment, and wherein the promoter is one or more selected from the group consisting of Na, K, Mg, Mn, Ru, Zr, Ce, and La.