Heterogeneous catalyst for transesterification and method of preparing same

Abstract

A transesterification catalyst that is heterogeneous and a method for preparing said transesterification catalyst are provided. The catalyst can be used in a variety of transesterification reactor configurations including CSTR (continuous stirred tank reactors), ebullated (or ebullating) beds or any other fluidized bed reactors, and PFR (plug flow, fixed bed reactors). The catalyst can be used for manufacturing commercial grade biodiesel, biolubricants and glycerin.

What is claimed is: 
     
       1. A transesterification catalyst comprising a double metal salt, wherein the double metal salt has the formula Z x Q y (PO 4 ) n H 2 O where x is a rational number in the range from 0.5 to 4, y is a rational integer in the range from 2 to 8, and n is a rational integer in the range from 4 to 8, and wherein the the double metal salt comprises a first metal phosphate with the metal selected from the group consisting of sodium and lithium and a second metal phosphate with the metal selected from the group consisting of calcium and barium. 
     
     
       2. The transesterification catalyst of  claim 1 , wherein the catalyst comprises a tri-basic compound formed from a mixture of a first metal hydroxide and a second metal hydroxide dissolved in phosphoric acid, wherein the metal of the first metal hydroxide is selected from the group consisting of sodium and lithium, and the metal of the second metal hydroxide is selected from the group consisting of calcium and barium. 
     
     
       3. The transesterification catalyst of  claim 1 , wherein the second metal is calcium. 
     
     
       4. The transesterification catalyst of  claim 2 , wherein the metal of the second metal hydroxide is calcium. 
     
     
       5. The transesterification catalyst of  claim 2 , wherein the first metal hydroxide and the second metal hydroxide are present in a ratio of about 1:10 by weight. 
     
     
       6. The transesterification catalyst of  claim 1 , wherein the catalyst is heterogeneous. 
     
     
       7. The transesterification catalyst of  claim 1 , wherein the catalyst is active at a temperature in the range from 40 to 70 degrees Celsius and at atmospheric pressure. 
     
     
       8. The transesterification catalyst of  claim 1 , wherein the catalyst is active at a temperature of up to 100 degrees Celsius and at atmospheric pressure. 
     
     
       9. A reusable transesterification catalyst comprising a double metal salt having the formula Z x Q y (PO 4 ) n H 2 O, wherein:
 Z consists of potassium,   Q consists of calcium,   x is a rational number in the range from 0.5 to 4,   y is a rational integer in the range from 2 to 8, and   n is a rational integer in the range from 4 to 8;   
       and wherein no leaching of metal ions from the catalyst into a transesterification reactant mixture occurs, and the catalyst is capable of being separated from transesterification reactants and products and reused, wherein the transesterification catalyst is supported on a ceramic substrate, and wherein the transesterification catalyst has an average pore diameter in the range from 1-10 nanometers and an active surface area greater than 20 m 2 /gm.