Conventional Process

Conventional Process
The most common catalysts used in the industry today are the bases sodium hydroxide or potassium hydroxide. In case the free fatty acid content in the oils is higher than 5%, an additional esterification step is required before the trans esterification to convert the FFA to triglycerides. Otherwise the amount of soap created in the process is higher. The soap needs to be washed out with a lot of water to ensure an efficient process and protect the equipment. This water needs to be treated before it can be safely disposed of. Some processes using waste oils as feedstock work around the esterification step by mixing oils with different levels of FFA to reduce the overall percentage.

The pressures and temperatures used in these chemical processes vary depending on the quality of the technology and equipment used. A typical temperature for base trans esterification is around 70°c and 270°c for acid esterification. The purity of the glycerin and methanol by-products and he percentage of oil successfully converted to biodiesel also vary. Average yield losses when making biodiesel out of waste oils are around 2% yield loss for every extra % in FFA. A usual process works in batches as it takes several hours for the catalyst to saturate the oil and convert it. Large facilities however may produce continuously as their scale permits more complicated set-ups.

Some companies have explored alternatives to the conventional process, such as putting the feedstock in a supercritical (extreme pressure and temperature) state or using enzymes as catalysts.
Contact Us: