When I set transesterification reaction with eggshell Cao and Beef fat/ palm oil, biodiesel was produced. But, When I set the reaction with the mixture of beef fat and palm oil (waste cooking oil or virgin palm oil), the reaction was never completed, I got only a homogeneous product of fat and oil only. even I have tried by varying the parameters like temperature (60, 70, 75), speed (500, 1100 rpm), reaction time (3, 4, 5, 5.30 hr), oil to methanol ratio (1:9, 1:12, 1:15, 1:20), catalyst loading (2.5%, 5%, 7.5%, 10%).
Please suggest to me what is the reason behind this and what would be the solution?
Dear Ameer Suhel,
I clearly understand the situation; if it works for both lipids independently, why not together?
First, you should note as I pointed out some time ago, "Use of heterogeneous catalyst for biodiesel production requires a lot of care..." (https://www.researchgate.net/post/Why-am-I-not-able-to-perform-reaction-with-CaO-catalyst-and-cooking-oil#view=5a988201f7b67e1b2d74c3f3).
To investigate that your catalyst is not posing the problem, kindly try the mixture with a homogeneous catalyst (KOH or NaOH). If it works well, try the lipids separately using your synthesized catalyst, this time around, roughly search for the best (optimal) conditions for transesterifying each of the lipid stocks. Now, try the mixture. The mixed lipid stock must transesterify at around the two determined optima. You may use centrifugation to enhance separation after each reaction but always test for solubility in water, in order not to mistake methanol for the biodiesel phase.
Beware! Each lipid feedstock must remain the same throughout the experiments. That means you must secure sufficient beef tallow, sufficient palm oil, and store them airtight at low temperature; those would be your stock. Representative samples must be taken each time you need them; melt and shake before taking samples from the stock (to avoid melting and shaking huge vessels each time, store the feedstock in several small-sized vessels).
Altogether, there should be no inhibiting effect of mixing triglycerides on their transesterification. Besides, palm oil and beef tallow share a similar fatty acid profile.
Cheers and best regards!
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