Vegetable oil sludge is a major byproduct of vegetable oil factories, and consists of triglycerides (61%), free fatty acid (37%) and impurities (2%). The hydrocarbon chains of triglycerides and free fatty acid are mainly made up of C₁₆ (30%) and C₁₈ (36%) hydrocarbons. The others consist of C₁₂–C₁₇ hydrocarbon chains.

The team synthesized a ZSM-5/MCM-41 multiporous composite (MC-ZSM-5/MCM-41) using silica source extracted from rice husk. The material has the MCM-41 mesoporous structure, and its wall is constructed by ZSM-5 nanozeolite crystals.

The results of vegetable oil sludge cracking reaction show that the product consists of fractions such as dry gas, liquefied petroleum gas (LPG), gasoline, light cycle oil (LCO), and (heavy cycle oil) HCO, which are similar to those of petroleum cracking process.

MC-ZSM-5/MCM-41 catalyst is efficient in the catalytic cracking reaction of vegetable oil sludge as it has higher conversion and selectivity for LPG and gasoline products in comparison to the pyrolysis process. Product distribution (% of oil feed) of cracking reaction over MC-ZSM-5/MCM-41 is coke (3.4), total dry gas (7.0), LPG (31.1), gasoline (42.4), LCO (8.9), HCO (7.2); and that of pyrolysis are coke (19.0), total dry gas (9.3), LPG (16.9), gasoline (28.8), LCO (13.7), and HCO (12.3).

—Nam et al.

The results indicate a new way to use agricultural waste such as rice husk for the production of promising catalysts and the processing of vegetable oil sludge to obtain renewable fuels, the team said.

Resources

• Le Thi Hoai Nam, Tran Quang Vinh, Nguyen Thi Thanh Loan, Van Dinh Son Tho, Bao-lian Su (2010) Preparation of bio-fuels by catalytic cracking reaction of vegetable oil sludge. Fuel, In Press, doi: 10.1016/j.fuel.2010.10.060