Hello folks,

We are two chemical engineer students trying to make biodiesel from animal fat. We ran into a problem during our first test batch. We did titrate our oil with NaOH and found out that we need 6g. NaOH/L. to neutralize the FFAs. Now the thing is, the melting point of our oil is at around 35C-40C.

We did our first batch at around 50C (reaction time one hour) but now everything solidified back at room temp.

Perhaps our oil is of very bad quality ? Please advice.


Thank you very much in advance.

quote:

Originally posted by Noxx:
Hello folks,

We are two chemical engineer students trying to make biodiesel from animal fat. We ran into a problem during our first test batch. We did titrate our oil with NaOH and found out that we need 6g. NaOH/L. to neutralize the FFAs. Now the thing is, the melting point of our oil is at around 35C-40C.

We did our first batch at around 50C (reaction time one hour) but now everything solidified back at room temp.

Perhaps our oil is of very bad quality ? Please advice.


Thank you very much in advance.

When reacting high animal fat content feedstock you need to keep everything warm. The normal melting point of animal fats is as you have noted at 35C to 40C. If you have very high conversion biodiesel you will still have a melting point probably >15C (depending upon the source of the animal fat)

Did you do a 27/3 test afetr you had finished the reaction, if you have low conversion then the amount of unconverted animal fats would raise the melting point and you could easily get above 20C.

I would suggst future batches you maintain temperature between 55C and 60C and make sure you don't add relatively cold methoxide.

When you say room temperature what temperature is it actually solidifying and what do you actually mean by "room temperature". 20C is typical "room temperature" at which you may well get some clouding in even high conversion fuel. This is one of the down sides of making Biodiesel from animal fats. other than the cold flow properties the reation with animal fats is normally quite straight forward.

How about reheating it?

use the acid method.

quote:

Originally posted by antifuel1:
use the acid method.

The acid method is not really going to improve the melting point of an animal fat based biodiesel. Especially if they already have high conversion fuel.

quote:

Perhaps our oil is of very bad quality ? Please advice.

Did you test for water content. Wet oil results in a poor reaction and high soap production, particularly in high titration oil.

That said, the freeze point of your oil will be indicitive of the freeze point of your finished BD. Blend your animal fat with canola oil if you want better cold weather performance.

Animal fat biodiesel is only good if you live at the Equator or plan on blending it at very low percentages. The basic chemistry of an acid (vegetable or animal) doesn't change THAT much through transesterification; IE: if it gels in it's raw state at room temperature it will more than likely also gel when biodiesel is made from it at or around the same room temperature.

Except for a very limited amount of oil I exclusively produce from animal fats, and yes the BD will gell at higher than that produced from oils but todate except for very cold times in the winter and then only early mornings do I have a problem with it. It still makes very good BD with very good seperation and yealds, I do process with Koh rather than Naoh.
In your post you said you tritated to 6gms has this calculation allowed for the base amount (I think 3-5 for Naoh others will correct if I am wrong here)the formular is base amount PLUS tritation, is just a thought. If the Naoh amount is to low the process will probably be incomplete ....regards Kev

quote:

We did titrate our oil with NaOH and found out that we need 6g.

Did it titrate at 1, and you used a base # of 5g/L? If not, 6 is likely too little catalyst. As has been stated, check conversion with a 3/27 test.