Study On Preparation Of Biodiesel Catalyzed By Solid Base Catalyst And Its Process

Solid catalyst is the one used mostly in industry which has the advantage of mild reactivity conditions, circular use feasibility, convenient separation, less environmental pollution and so on. It can make up the shortage of catalyst presently used in biodiesel preparation. Therefore, the preparation and study on high efficient solid catalyst can overcome the difficulties in bio-preparation.In this paper, the solid acid catalyst and solid alkali catalyst were prepared and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and then applied to the preparation of biodiesel. The main conclusions were as follows:(1) The solid acid catalyst was prepared and characterized by XRD and TEM. The results showed that high dispersity and good crystal effect of active component of the catalyst was achieved when preparing Zr-modified Solid Super Acid S₂O₈^2--TiO₂/Fe₃O₄ under following conditions: the mol ratio of Zr to Ti 7:300, baking temperature 450℃, baking time 3h, and crystals with a 40-60 nm diameter were formed which remained good magnetism.(2) The solid alkali catalyst was prepared and characterized by XRD. It was found that high dispersity and balanced alkali sites of the catalyst was achieved when the quality of load KNO₃ was 20% that of its carrier ZrO₂, drying temperature 110℃, baking temperature for activation 700℃, baking time 4h.(3)The solid acid catalyst was applied to biodiesel preparation and the technics was optimized by sigle-factor and orthogoral experiments with esterification rate as the index. The optimal conditions were: reaction temperature 65℃, reaction time 6h, the quality of catalyst 12% that of fatty acid, 3ml methanol per gram fatty acid, under which the esterification rate could amount up to 94.48%.(4)The obtained solid alkali catalyst was applied to biodiesel preparation with colza oil and used oil as materials respectively and the technics was optimized by sigle-factor and orthogoral experiments with esterification rate as the index. The optimal technique conditions using colza oil were: the amount of solid catalyst 12%, the mol ratio of methanol to oil 9:1, reaction temperature 65℃, reaction time 3h, under which the esterification rate reached to 94.48%. The optimal conditions using used oil were: the amount of solid catalyst 4%, the mol ratio of methanol to oil 6:1, reaction temperature 65℃, reaction time 3h, under which the esterification rate reached to 91.2%. (5)The components of refined biodiesel were analyzed by GC. The content of fatty acid methyl ester reached to 98.03% by fatty acid methyl esterification, and 98.53% with used oil as the material.