At this site they talk about using methanol, used oil, and lime to make biodiesel with near 100% conversion at 60 degrees reaction temp. http://pubs.acs.org/cen/news/89/i25/8925scene4.html Not much detail but eliminates some dangerous chemicals. May also be less expensive, have not looked up the price of lime.
It appears to be reasonably simple. The process is detailed here:
Commercial Hydrated Lime as a Cost-Effective Solid Base for the Transesterification of Wasted Soybean Oil with Methanol for Biodiesel Production
what I would like to know is just how it works. Is the lime that they are talking just the lime that is used on fields? If so it is really inexpensive. From the article it is a solid base that will work only 3 times before replacement. How much are they using mixed in as a powder, or does come in a larger size that is put in a cage with the pump inline, etc.
I think I am going to have to put on a mad scientist hat and see what kind of experiments I can come up with.
Notice the required temperatures, 200 to 500 C. The methanol must be under high pressure.
Those are not reaction temperatures. Go back and read the paper carefully. Note the graphs.
If you go the the link provided in the message above yours and read the paper then your questions should be answered. There isn't much info in the news release first posted.
Without me spending $35 to get the document, do they mix up titration solution with hydrated lime, the same as you would with NaOH and then mix it with the methanol for the reaction?
I am curious about the 100% conversion claim. Most other processes claim high 90s but 100% is better. Did they use a gas chromatigraph to determine the conversion level?
I downloaded the article without paying anything
Nope,I cannot download it either-apparently do not have the right credentials!
If you have read it John,could you give a few pointers of how they are adding the lime-I want to try this on a Dr pepper if it is doable
John, did you get the full detailed paper without paying. I certainly can't get it thorugh the site you have linked to.
Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca(OH)2. It is a colourless crystal or white powder and is obtained when calcium oxide (called lime or quicklime) is mixed, or "slaked" with water. It has many names including hydrated lime , builders lime, slack lime, cal, or pickling lime. It is of low toxicity and finds many applications. [from WikiP]
relevant excerpts from the research paper Commercial Hydrated Lime as a Cost-Effective Solid Base for the Transesterification of Wasted Soybean Oil with Methanol for Biodiesel Production :
2. EXPERIMENTAL SECTION
2.1. Materials. Hydrated lime (HL), purchased from Cales Santa
Emilia ubicated in Perote, Veracruz, Mexico, is sold in 25 kg paper sacks
and was used as received without further purification. Virgin soybean oil
was purchased from a local store. The used soybean oil (USO) was
obtained by frying six batches of potatoes in virgin soybean oil. Then, it
was filtered under vacuum to eliminate the suspended solids followed by
heating to remove all the moisture. Methanol (98% purity) was purchased
from Golden Bell. Methanol was dried with metallic magnesium
2.3. Transesterification of Used Soybean Oil with Methanol.
The experiments were conducted in a 100 mL three-neck glass flask
coupled to a condenser and a water cooling recirculation system. Stirring
and heating were achieved using a magnetic stirrer/hot plate.
First, the USO was heated above 100 C for 1 h to eliminate moisture
and then the oil was cooled to the required reaction temperature.
Methanol and the catalyst were separately added into the glass flask.
Then, USO was charged into the vessel and heated to the intended
After the course of the reaction, the reaction mixture was centrifuged
and the liquid phases were separated from the catalyst and decanted in a
separation funnel. Excess methanol was removed by evaporation, leaving
BD and glycerol as separate phases. The BD was analyzed by thinlayer
chromatography (TLC) and proton nuclear magnetic resonance
(1H NMR) analysis.
In order to evaluate the optimal reaction conditions of the
transesterification process with the as-received hydrated lime, we
examined the effect of the following reaction parameters: reaction
time, catalyst amount, and methanol-oil ratio, and reaction
temperature. The initial reaction conditions were 12 mL of USO,
6 mL of methanol, 1 g of catalyst, and a reaction temperature of
3.2.2. Reaction Time Effect. Figure 6 exhibits the influence of
reaction time at 10, 30, 60, and 120 min. From the results
obtained, it is evident that reaction time affected significantly the
catalytic activity, since the conversion percentage gradually
increased with the reaction time, achieving in 10, 30, 60, and
120 min conversions of 12, 58, 86, and 100%, respectively.
3.2.3. Effect of Catalyst Loading. The effect of the catalyst
loading on BD production is shown in Figure 7. The studied
range was 0.30.60 g (2.14.2% in relation to the mass of the
USO and methanol). As can be observed, the conversion
percentage increase was proportional to the catalysts loading.
The best result was obtained with a catalyst amount of 0.57 g,
which corresponds to a weight ratio of 4%. With 4% of catalyst,
2 h is enough to reach the complete conversion of the raw
3.2.4. Effect of the Methanol:Oil Ratio. Theoretically, to carry
out the transesterification reaction, 3 mol of alcohol is required
for 1 mol of triglyceride to produce 3 mol of fatty acid ester and
1 mol of glycerol. It is well-known that the transesterification
reaction is a reversible one, and with the intention to shifting the
equilibrium toward biodiesel production, an excess of methanol
is generally employed. Thus, the yield of biodiesel is increased
when the alcohol:triglyceride ratio is raised above 3 and reaches a
maximum. It is important to consider that increasing the alcohol
amount beyond the optimal ratio will not increase the yield but
will increase the cost for alcohol recovery. The stoichiometry of
this reaction requires 0.134 volume of methanol per volume of
triglyceride (the molar ratio is 3:1).32 Taking this into account,
the methanol-oil ratio (vol) was varied from 0.08 to 0.5.
The experimental results, illustrated in Figure 8, demonstrate
the significant impact on biodiesel obtained since the conversion
increased with the increment of the methanol-oil ratio from 0.08
to 0.17, achieving conversions of 73 and 100%, respectively.
Although conversions higher than 97% were obtained with
higher methanol-oil ratios, the methanol excess could raise the
biodiesel cost due to the additional process needed for alcohol
recovery, as stated before.
3.2.5. Effect of Reaction Temperature. To elucidate the effect
of reaction temperature, the transesterification of USO was
conducted with the fresh HL, Ca(OH)2, and with ...(CaO), maintaining constant the catalyst
amount (4%), 0.17 methanol-oil ratio (vol), and 2 h reaction
time. The results are presented in Figure 9. The results revealed
that conversion of the raw materials increased with the reaction
temperature. No conversion was achieved with the fresh HL at
25 C, while at 35, 45, 55, and 60 C conversions of 2, 19, 57 and
100% were accomplished, correspondingly. On the other hand,
by using ...(CaO), conversions of 45, 89,
91, 93, and 100% were achieved at 25, 35, 45, 55, and 60 C,
3.2.6. Catalyst Reutilization. Recovery and reuse of the catalyst
is one of the most important characteristics of heterogeneous
catalysis which also would impact the economics for biodiesel
production. Reutilization of the catalyst was carried out by
recovering the liquids after a catalytic run, maintaining the
catalyst inside the reactor, and adding new fresh portions of
methanol and used soybean oil. From the above-studied reaction
parameters the operating conditions for the reutilization study
were 2 h of reaction time, methanol-oil ratio (vol) of 0.17, catalyst
concentration of 3.6 wt %, and a reaction temperature of 60 C.
The catalyst was highly active up to the second reutilization,
which means, after using the catalyst three times, a 100%
conversion was achieved. However, an important decrease was
identified in the third reuse, reaching a conversion of 62%.
In this work an environmental friendly process for biodiesel
production was developed. As-received hydrated lime and the
products of its thermal decomposition were evaluated in the
transesterification of used soybean oil and methanol. It was
demonstrated that hydrated lime did not required an activation
process for achieving a complete conversion of the raw materials
into biodiesel. From the XRD analysis it was confirmed that the
active phase was calcium hydroxide, so it was established that
surface Br€onsted basic sites of Ca(OH)2 were highly active in the
transesterification reaction. Moreover, 100% conversion was
obtained up to the second reuse of the catalyst without any
special reactivation procedure. Due to its low cost, commercial
availability, resistance to atmospheric poisoning, and reusability,
hydrated lime represents a new alternative for lowering the cost
of biodiesel production.
*Phone: + (5255) 2295500, Ext. 7254. E-mail: manuel.sanchez@
To view or download the full article go to the link in the first message, then click on the link in the first paragraph. That takes you to a page where the PDF links work. ...or at least it does if using Firefox This link seems to work to access the full article with Firefox if one follows the steps outlined above.
If it doesn't work then send me a PM with an e-mail and I will send you a PDF copy of the paper.
This looks like a good way to limit use of hazardous chemicals by removing one anyway, and lots less expensive than naoh or koh. Wonder how the leftovers would do in soap making?
I would be interested in a full copy of that.
Done... good find Dan...thanks
Figure 6 exhibits the influence of reaction time at 10, 30, 60, and 120 min. From the results obtained, it is evident that reaction time affected significantly the catalytic activity
Figure 7. The best result was obtained with a catalyst amount of 0.57 g with 12 ml USO and 6 ml methanol, which corresponds to a catalyst/liquid weight ratio of 4%
The experimental results, illustrated in Figure 8, demonstrate the significant impact on biodiesel obtained since the conversion increased with the increment of the methanol-oil ratio from 0.08 to 0.17, achieving conversions of 73 and 100%, respectively.
To elucidate the effect of reaction temperature, the transesterification of USO was conducted with the fresh HL, Ca(OH)2, and with ...(CaO), maintaining constant the catalyst amount (4%), 0.17 methanol-oil ratio (vol), and 2 h reaction time. The results are presented in Figure 9.
ABSTRACT: The transesterification of used soybean oil with methanol was carried out over hydrated lime (HL), Ca(OH)2, and its decomposition products in the 200-500 C range. The catalysts were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis, and scanning electron microscopy. The XRD powder patterns demonstrated that the pristine sample consisted of a mixture of calcium hydroxide and calcite. It was noticed that the coexistence of CaO, Ca(OH)2, and CaCO3 remained up to 400 C. At 500 C, Ca(OH)2 is transformed into CaO so that this and CaCO3 are the only remaining phases.
In the transesterification reaction, the influence of calcination temperature, reaction time, catalyst amount, methanol-oil ratio, and reaction temperature was studied. Full conversion of the raw materials into biodiesel (BD) was obtained with the fresh HL. In order to determine any change in the solid, it was recovered after 10, 30, and 60 min of reaction and analyzed by XRD analysis. Only Ca(OH)2, CaCO3, and traces of monohydrocalcite were detected.
From the results it was demonstrated that the active phase for biodiesel production was calcium hydroxide. Furthermore, the catalyst was used up to three times without deactivation.
A simple, economic, and environmentally friendly way to obtain biodiesel was developed considering (a) used soybean oil, considered waste, was employed as raw material, (b) hydrated lime is cheap and readily available, and (c) full conversion of the raw materials into BD was achieved with the as-received HL.
Thanks John-nice one
I'd guess 1200 ml UCO + 600 ml methanol + 57 gm Hydrated Lime should work for a test/sample batch to duplicate their experiment in a 2L bottle.
Post your results. I will try it when I can find some lime and time.
I'll probably try half those numbers,just so lots of room for shaking/mixing.I will post what happens.
Got to find some lime now-Can't help thinking "quick lime" CaO might be more active,but the text says hydrated lime,so that is what I will try.
Seems to good to be true,but lets see what pans out
Figure 9 shows the reaction with quick lime CaO vs. slaked lime Ca(OH)2 as the catalyst.
It appears that CaO could use a lower reaction temperature.
Using 20% methanol would reduce the catalyst to 42 gm for 1 L UVO and 200 ml methanol
Sounds interesting...but, I have a real vague recollection of reading something eons ago mentioning that virtually any hydroxide combo would work(KOH, NaOH, CaOH etc) but that keeping a number of them in suspension was difficult because of the quantity needed, particularly if you're trying to use it to neutrize the FFA's with it. 4% by weight is doable, but that's with new oil - get to 10+% it's going to be much harder.
According to the article they bought new oil and then used it to make fries etc. My next question is that they used this for used soy oil, will it work for other oils or only soy? I am going to have to play with this a little.
I am too new at this to make lots of assumptions.
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