Method for preparing 1,3-propanediol with high space-time yield and high concentration

A method for preparing 1,3-propanediol, comprising:

• pumping, by a feed pump, a methyl 3-hydroxypropionate solution into a tubular fixed-bed reactor for hydrogenation to obtain a reaction mixture, wherein the tubular fixed-bed reactor is loaded with a surface modifier-coated nano-Cu-based catalyst;
• a concentration of methyl 3-hydroxypropionate in the methyl 3-hydroxypropionate solution is 90-99 wt. %;
• and the nano-Cu-based catalyst comprises an active component, an additive component, and a carrier, wherein the active component is Cu, and the additive component is a metal oxide of XOn/2, wherein a metal in the metal oxide is represented by X;
• subjecting the reaction mixture to rectification to separate light components from heavy components, wherein the light components comprise methanol, n-propanol, methyl propionate, methyl 3-hydroxypropionate and 1,3-propanediol;
• and the heavy components comprise 1,3-propanediol mono-propionate and 1,3-propanediol mono-3-hydroxypropionate;
• and
• feeding the heavy components back to the tubular fixed-bed reactor for secondary hydrogenation;
• and subjecting the light components to separation to collect 1,3-propanediol;
• wherein the surface modifier-coated nano-Cu-based catalyst is prepared through steps of:
• (1) mixing a copper precursor and an Xn+ precursor in a preset weight ratio to form a mixed aqueous solution with a molar concentration of 0.1-1 mol/L;
• (2) preparing a base solution with a molar concentration of 0.5-5 mol/L as precipitant;
• (3) adding a sol or nano-powder of SiO2 and SnO2 to a cooled aqueous solution containing an organic polyol to form a carrier mixture solution;
• (4) simultaneously adding the mixed aqueous solution and the base solution to the carrier mixture solution under stirring for co-precipitation to form a slurry, wherein a pH of the slurry is kept at 10-12 during the co-precipitation;
• (5) after the co-precipitation is completed, heating the slurry to 80-100° C. for aging for 2-24 h, followed by filtration, washing, atmospheric-pressure drying, and calcination to obtain a nano-Cu-based catalyst precursor;
• (6) subjecting the nano-Cu-based catalyst precursor to impregnation with a surface modifier, drying and calcination to obtain a catalyst powder;
• and
• (7) subjecting the catalyst powder obtained from step (6) to pressing-sieving or extrusion, and reduction activation to obtain the surface modifier-coated nano-Cu-based catalyst;
• wherein the surface modifier is selected from the group consisting of an organic aluminum salt, an organic zirconium salt and a combination thereof;
• the base solution is one or two of sodium hydroxide, sodium bicarbonate, sodium carbonate, ammonium carbonate, ammonium bicarbonate and ammonia;
• the carrier is a SiO2—SnO2 composite;
• and
• X is selected from the group consisting of Zn, Ga, Ge, In, Y, Ce, Ho and a combination thereof.