BRPI0902550A2 - blond glycerin purification process from biodiesel transesterification - Google Patents

Abstract

PURIFICATION PROCESS OF BLONDE GLYCERIN, ORIGINATED FROM BIODIESEL TRANSESTERIFICATION. The present invention describes a practical method of purifying blond glycerin from biodiesel production, free from distillation under reduced pressure and without the need for medium neutralization via chemical agents classified as organic or inorganic bases. In the present purification process acetals and ketals are produced from the cyclization of the respective triol in the presence of different aldehydes and ketones in the absence of additional acid catalysts. The cyclized adducts are hydrolyzed to different concentrations of distilled water and glycerine is recovered with degree. purity ranging from 90 to 99.9%, and chemical yield is quantitative.

Description

BLOND GLYCERIN PURIFICATION PROCESS, ORIENTED BIODIESEL

Field of Invention

The present invention describes a practical method of purifying blond daglycerin from biodiesel production, free from distillation at reduced pressure and without the need for medium neutralization via chemical agents classified as organic or inorganic bases. In the present purification process, acetals and ketals are produced by cyclizing the respective triol with different ketones and aldehydes in the absence of additional acid or basic catalysts. After the cyclic intermediates were hydrolyzed, the purified glycerin was recovered to excellent yields.

Background of the Invention

Most of the energy consumed in the world comes from oil, charcoal and natural gas. These sources are not renewable and are expected to run out in the future. Therefore, the search for new sources of energy is of no importance. This constant search has resulted in the discovery of the potential demonstrated by biomass that appears as an alternative source to solve the worldwide energy problem.

Energy generated by biomass can be defined as that which is supplied by materials of plant origin or obtained by the decomposition of waste. Brazil has sought to use biomass as a renewable source of energy, among which are: firewood, babassu, vegetable oils, vegetable waste, sisal, biogas, rice husks, sugarcane (sugarcane bagasse, straw and alcohol).

Among the most researched energy sources, vegetable oils stand out, being their use tested in the late nineteenth century, producing satisfactory results when tested in diesel engines. The possibility of using biofuels of plant origin is very attractive, considering the environmental and economic aspects. It has been found, however, that the direct application of nosmotor vegetable oils is limited due to their physical properties, such as their high viscosity, low volatility, polyunsaturated character, acidity that cause problems in the internal parts of the engines, due to incomplete combustion. Thus, aiming at reducing the viscosity of the raw material, different alternatives have been considered, such as addition, microemulsion using methanol or ethanol, catalytic cracking and transesterification with ethanol or methanol, promoting the obtaining of biodiesel, according to reaction. below, down, beneath, underneath, downwards, downhill:

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Although biodiesel generation is advantageous over fossil fuels, the co-production of impure and low-cost glycerine in a proportion of about 10% by mass is inevitable.

There is a wide need for increased scientific / technological research, referring to the purification of glycerin from biodiesel production processes, which may become an important raw material for the chemical industry, occupying a considerable portion of naphtapetochemistry in the production of plastics and other derivatives. chemicals of higher added value. In the scientific literature, information has been found that the share of biodiesel in Brazil's energy matrix tends to rise from 3% in 2008, the so-called B3, to 5% in 2013 (B5), with the view that these rates increase to B20 in 2008. 2020

Growing concern about global warming, sparked worldwide discussions about new, less polluting energy sources. Modern society is increasingly dependent on oil, but is already considering the viability of renewable fuels, which would have a much smaller impact on global warming, because in the overall balance, CO2 emissions, one of the main villains of the greenhouse effect, decrease.

There are still some vagueness of what biodiesel is, and a mixture of vegetable oils and diesel may be considered, or it may be considered as a monoalkyl ester of fatty acids derived from renewable sources, such as vegetable oils and animal fat, through a process in which triglycerides break down, producing molecules of lower molecular weight, classified as fatty acid esters or even after the transfer of vegetable oils used in frying, in domestic or industrial sewage.

Regardless of the definition, biodiesel from vegetable oils or from original oils generates about 10% of crude glycerin, which is difficult to treat.

Glycerin, known as 1,2,3-propanotriol, is a highly functionalized, proquiral and biodegradable molecule. It can be found in vegetable oils in the form of fatty triglycerides or as an intermediate in the metabolism of living organisms.

Glycerin is usually obtained through the process of manufacturing soap, fermentation by microorganism (wine and beverage generation), production of fatty acids, and can also be obtained through depropylene oxide in the processing of petroleum derivatives.

With the introduction of biodiesel in the market, about 800,000 tons of glycerin were traded worldwide in 2005, according to Pagliaro in his article entitled "From Glycerol to Value-Added Products." The forecast for Brazil indicates that there will be a production of 120,000 tons per year of glycerine with the entry of B3 and 200,000 tons per year from 2013, with the use of B5. This surplus of glycerin is much larger than the national production and consumption, estimated today around 30 to 40 thousand tons per year.

For the Brazilian Biodiesel Technology and Use Program to be successful, it is important to investigate economically viable solutions for glycerine purification in order to re-introduce it into the chemical chain as a higher added value feedstock, since the price of this fuel product in its raw form is getting lower and lower.

For glycerin purification, two methods described in the literature are the most used. These methods are known as "conventional process" and "ion exchange" and are the most widely used by industries. However, they have serious problems.

The conventional process consists of the addition of HCl and FeCl3 to glycerinabruta in order to keep the pH between 4 and 4.5, in order to eliminate soaps and other organic impurities. Then the formed fatty acids are filtered and the filtrate is neutralized with NaOH to pH 6.5. After treatment the crude glycerin will contain water, NaCl, methanol and residues of other organic matter. The filtrate is then evaporated to 80 to 90% glycerine (by mass).

This procedure is an adaptation of US patent No. 04655879 and is one of the most energy-consuming operations, generally occurring at reduced pressures (46.7 mm Hg in the first stage and 18.67 mmHg in the second stage), which makes degradation difficult. of glycerin above 200 ° C.

During the evaporation of water it is inevitable that the concentration of inorganic salts that begin to crystallize and therefore need to be continuously removed from the system through the evaporator bottom to avoid scale in the equipment. Then the recovered glycerin is brought to a centrifuge. The remaining dissolved salt is sedimented in conical tanks for six hours for separation. The supernatant glycerin is then stored and can be sold as a technical grade glycerin. To obtain a USP-grade glycerin, it is refined by distillation. As glycerin polymerizes and decomposes at temperatures above 200 ° C, distillation should always be performed at reduced pressure.

In the process involving ionic resins, crude glycerin is treated in a similar manner to the conventional process until the neutralized filtrate is obtained. Then purification is by ion exchange, which consists of passing the filtered material through successive beds of strong cationic resin, weak anionic resin and strong cation and anion mixed resins. Note that ion exchange units work efficiently for dilute solutions containing from 20 to 40% glycerin. The material is passed through the resin bed (see US Patent No. 0 0249338) with traces of free fatty acids, color, odor and other mineral impurities present. At this stage, glycerine is purified by vacuum evaporation, using multiple effect evaporators, so that in the end a glycerine of more than 99% purity is obtained.

The French patent, FR No. 578306, describes a heterogeneous hazeotropic distillation process which served as the basis for the development of a method for purifying crude glycerin and obtaining it with high purity. In this process, a solution of the crude material is pumped to a Heating chamber for steam generation that suffers condensation in perforated plates planned in a distillation column. Although apparently a practical alternative for industrial use, the procedure demonstrates difficulties in reproducibility of the results, since the work is directly linked to the process variables such as glycerine feed (g / s), toluene vapor feed (g / s), glycerine feed temperature (0C), initial glycerin concentration (% by mass), glycerine outlet concentration, and make use of toxic solvents such as toluene and benzene.

Two US patents, US Patent No. 0187281 and US Patent No. 6548681, disclose a procedure for purifying polyols or multiple polyols from an aqueous solution at different concentrations by cyclizing with aldehydes and ketones containing from 1 to 4 carbon atoms. The products obtained, called acetals and ketals, are separated at elevated temperatures. Even with a lower boiling point than the polyols themselves, water is still a limiting factor for this process. The recovered material is submitted to a reactor where the hydrolysis reaction occurs in the presence of mineral acids or ion exchange resins. Another process similar to that described above can be found in French patent FR 0 833607.

U.S. Patent No. 5,527,974 discloses a purification process for glycerin obtained from high pressure hydrogenation (100 bar and temperatures from 100 ° to 250 ° C) involving natural fats. After hydrogenating the fat, glycerin containing traces of fatty acids and other impurities is forced through a column containing a membrane that simulates microfiltration. The process is inefficient as clogging problems are frequent throughout the operation.

Summary of the Invention

It is an object of the present invention to describe a purification process of blonde glycerin from biodiesel production which comprises two distinct steps without the need for reduced pressure distillation and complete recovery of carbonylated agents. The reaction that served as the basis for the studies developed is the acetalization and / or ketalization reaction of glycerin using different ketones and aldehydes. It is noteworthy that the documents found in the patent literature do not invalidate the studies of the respective invention, serving only as a support for the development of an easy to handle, reproducible, fast and low cost process.

Description of the Figures

Figure 1 shows the chromatogram for follow-up of hydrolysis of blond glycerin-derived ketal with equimolar amount of distilled water at time intervals of 5 minutes, 30 minutes and 75 minutes. Figure 2 shows the chromatogram for dacyclohexanone-derived ketal.

Figures 3 and 4 show infrared spectra for glycerin PA and blonde glycerin after treatment according to the procedure described in this invention. Detailed Description of the Invention

This invention describes the ketalization and acetalization reactions of blonde daglycerin in the presence of propanone, or cyclohexanone, or 3-methyl-2-butanone, or formaldehyde, or acetaldehyde, or benzaldehyde, among other cyclization reagents, as shown below:

Blonde Glycerin

The glycerin samples obtained after the biodiesel transesterification process came from different oilseeds, such as: soybean oil, palm oil, sunflower oil, canola oil, jatropha oil, cottonseed oil, tallow, sunflower, babassu, forage turnip , coconut, rapeseed, among others, as well as glycerin generated from blends. The different glycerin samples investigated presented high content of fatty acids, decatalyst traces and alcohols.

The cyclization reaction involving the different ketones and aldehydes occurred at temperatures ranging from 25 to 100 ° C, under stirring in an open system without the need for an acid catalyst addition. Glycerin samples already had sufficient acidity (pH ~ 1.0) for which even partially, at room temperature. Staging does not exclude the use of purified glycerin, pharmaceutical grade glycerin, white glycerine, bidistilled, provided that in the presence of a catalyst.

In all experiments presented here, the best molar reference ratio for cyclization reagents (aldehydes and ketones) was between 1.0 and 3.0.

For the highest boiling reagents, the most suitable molar ratios were 1.05, 1.10 and 1.20. In all studied examples, the reaction time did not exceed 60 minutes. The best range is between 5 and 45 minutes, more specifically between 20 and 30 minutes.

After the GCMS (Gaschromatography-mass spectrometry) reaction was terminated, the cyclic intermediates were diluted with a small amount of acetone and filtered to completely remove precipitated impurities throughout the reaction, concentrated to hydrolyze with equimolar distilled water in a proportion ranging from 1.0 to 3.0. The temperature range used is between 50 and 90 ° C. The time interval for complete cleavage of cyclic intermediates did not exceed 120 minutes. The recovered clear glycerine solution was stirred for stirring in the presence of activated charcoal and / or diatomaceous earth for a period of 10 minutes and then filtered. After filtration, the material was evaporated and the ketone or aldehyde could be recovered when they had a low boiling point. Glycerin was recovered in yields ranging from 85 to 99.9% with purity above 90% and pH ranging from 6.5 to 7.2.

The following examples illustrate, without limitation, the scope of the present invention in order to detail the methodology used.

Example 1

In a 50 mL two-necked flask, a reflux condenser was coupled. The system was placed in a desilicone oil bath with the temperature set within a range of 40 - 60 ° C. Then, the system was charged with 2.000 g (21.74 mmol) of blond glycerin (pH = 1.0) and 10 mL of acetone PA, remaining under stirring for a period of time ranging from 5 to 20 minutes. Following the reaction by gas chromatography revealed a single product derived from cyclization. After finding the total consumption of the starting material, the acidity was monitored eο ρΗ ~ 5.0. In the first few minutes of reaction, it was possible to observe appreciation of the impurities contained in the blonde glycerin, being easily removed through a simple filtration. The clear characteristic solution was concentrated to give an oil in quantitative yield.

The recovered material was transferred to a 50 mL two-necked flask coupled to a reflux condenser. The system was placed in a silicone oil bath with the temperature set to 75 ° C and the medium treated with 1.10 to 1.50 equivalent of distilled water, remaining under constant agitation for a period of 50 to 80 minutes. of the total consumption of the starting material, the solution was activated with activated charcoal, remaining under stirring for an additional 10 minutes. Then the solution was filtered and concentrated to give 99.9% purity glycerin and quantitative chemical yield. Figure 1 shows the chromatograms for ketal and aglycerin after hydrolysis is completed. In figure 3, it is possible to observe the infrared spectrum of glycerin PA being compared to the infrared spectrometer of purified glycerin.

After all reaction parameters were determined, further experiments were performed to increase the amount of blond glycerin. The investigated masses ranged from 10 to 1000g and the molar ratio of acetone used was optimized from 6.25 to 1.10.

Example 2

In a 50 mL two-necked flask, a reflux condenser was coupled. The system was placed in a desilicone oil bath with the temperature set within a range of 80 - 100 ° C. The system was then loaded with 2,000 g (21.74 mmol) of blonde glycerin (pH = 1.0) and 2.224 g (22.82 mmol) or 2.36 mL of cyclohexanone, remaining under agitation for a period of time. which ranged from 10 to 30 minutes. Monitoring the reaction by gas chromatography revealed two isomeric products derived from cyclization. After finding the total consumption of the starting material, the acidity was monitored and the pH ~ 4.5. In the first minutes of reaction, it was possible to observe the precipitation of the impurities contained in the blonde glycerin, being easily removed by a simple filtration. The clear solution was concentrated to give an oil in quantitative yield.

The recovered material was transferred to a 50 mL two-necked flask coupled to a reflux condenser. The system was placed in a silicone oil bath with the temperature set to 80 ° C and the medium treated with 1.00 to 1.30 equivalent of distilled water, remaining under constant agitation for a period of 95 to 120 minutes.

After finding the total consumption of the starting material, the solution was activated with activated charcoal, remaining under stirring for an additional 30 minutes. Then the solution was filtered and concentrated to give 95% purity glycerin and quantitative chemical yield.

Example 3

In a 50 mL two-necked flask, a reflux condenser was coupled. The system was placed in a desilicone oil bath with the temperature set within a range of 90 - 100 ° C. The system was then charged with 2,000 g (21.74 mmol) of blonde glycerine (pH = 1.0) and 1.872 g (21.74 mmol) or 2.32 mL of 3-methyl-2-butanone, remaining over-agitation for a period of time ranging from 25 to 40 minutes. Monitoring the reaction by gas chromatography revealed two isomeric products derived from cyclization. After finding the total consumption of the starting material, the acidity was monitored and the pH ~ 5.0. In the first minutes of reaction, it was possible to observe the precipitation of the impurities contained in the blonde glycerin, being easily removed by a simple filtration. The clear solution was concentrated to give an oil in quantitative yield.

The recovered material was transferred to a 50 mL two-necked flask coupled to a reflux condenser. The system was placed in a silicone oil bath with the temperature set to 80 ° C and the medium treated with 1.10 to 1.40 equivalent of distilled water, remaining under constant agitation for a period of 30 to 80 minutes.

After finding the total consumption of the starting material, the solution was activated with activated charcoal, remaining under stirring for an additional 15 minutes. Then the solution was filtered and concentrated to give 90% purity glycerin and quantitative chemical yield.

Example 4

In a 50 mL two-necked flask, a reflux condenser was coupled. The system was placed in a desilicone oil bath with the temperature set within a range of 80 - 100 ° C. The system was then charged with 2.000 g (21.74 mmol) of blonde glycerine (pH = 1.0) and 2.31 g (21.74 mmol) or 2.20 mL of benzaldehyde, while stirring for a period of time. which ranged from 30 to 40 minutes. Follow-up of the reaction by gas chromatography revealed two isomerization products derived from cyclization. After finding the total consumption of the divided material, the acidity was monitored and the pH ~ 4.0. In the first few minutes, it was possible to observe the precipitation of blond naglycerin impurities, which were easily removed by simple filtration. The clear characteristic solution was concentrated to give a quantitative yield oil.

The recovered material was transferred to a 50 mL two-necked flask coupled to a reflux condenser. The system was placed in a silicone oil bath with the temperature set at 90 ° C and the medium treated with 1.10 to 1.30 equivalent of distilled water, remaining under constant agitation for a period of 50 to 70 minutes. of the total consumption of the starting material, the solution was activated with activated charcoal, remaining under stirring for an additional 30 minutes. Then the solution was filtered and concentrated to give 93% purity glycerin and quantitative chemical yield.

Example 5

In a 50 ml two-necked flask, a reflux condenser was coupled. The system was placed in a desilicone oil bath with the temperature set within a range of 30 - 45 ° C. The system was then charged with 2.000 g (21.74 mmol) of blonde glycerine (pH = 1.0) and 1.43 g (32.61 mmol) or 1.83 mL of acetaldehyde, while stirring for a period of time. which ranged from 50 to 70 minutes. Follow-up of the reaction by gas chromatography revealed two isomerization products derived from cyclization. After finding the total consumption of the divided material, the acidity was monitored and the pH ~ 5.0. In the first few minutes, it was possible to observe the precipitation of blond naglycerin impurities, which were easily removed by simple filtration. The clear characteristic solution was concentrated to give a quantitative yield oil.

The recovered material was transferred to a 50 mL two-necked flask coupled to a reflux condenser. The system was placed in a silicone oil bath with the temperature set at 75 ° C and the medium treated with 1.05 to 1.20 equivalent of distilled water, remaining under constant agitation for a period of 60 to 80 minutes.

After finding the total consumption of the starting material, the solution was activated with activated charcoal, remaining under stirring for an additional 20 minutes. Then the solution was filtered and concentrated to give 97% purity glycerin and quantitative chemical yield.

Claims (10)

1.) Purification process of blonde glycerin from biodiesel transesterification, comprising the following steps: (a) reacting blonde glycerin with a constant stirring cyclization reagent at 25 to 100 ° C in an open system without the addition of a b) after completion of step a) dilute the cyclic comacetone intermediates c) filter the cyclic intermediates to remove precipitated impurities throughout the reaction step d) hydrolyze the material that was filtered out in step c) thus a clear solution, e) stirring the solution obtained in d) in the presence of activated charcoal and / or terradiatom for a period of time between 10 and 30 minutes; and f) filtering and concentrating the solution from step e) thus obtaining a high purity umaglycerin. Process according to claim 1, characterized in that the blonde glycerin fat comes from soybean oil, palm oil, sunflower oil, decanola oil, jatropha oil, cottonseed oil, tallow, sunflower, babassu, turnip , coconut, rapeseed, among other oilseeds, or from the transtransification of vegetable oils used in frying, animal fat, domestic or industrial sewage. Process according to Claim 1, characterized in that the cyclization reagents are propanone (acetone), cyclohexanone, 3-methyl-2-butanone, formaldehyde, acetaldehyde, benzaldehyde. Process according to Claim 1, characterized in that the molar ratio between the cyclization reagent and glycerin is between 1 and 3. Process according to Claim 4, characterized in that the molar ratio between the cyclization reagent and glycerin is preferably 1.05, 10, and 1.20. Process according to Claim 1, characterized in that the time in step (a) does not exceed 60 minutes. Process according to Claim 1, characterized in that the molar ratio between the material filtered in step c) and water is in the range 1.0 to 3.0. Process according to Claim 1, characterized in that the temperature during step d) remains in the range of 50 to 90 ° C and the time interval for complete hydrolysis does not exceed 120 minutes. Process according to any one of claims 1, 2, 3, 4, 5, 6, 7 or 8, characterized in that the glycerin recovery process has a yield of between 85 and 99.9%. Process according to any one of claims 1,2, 3, 4, 5, 6, 7, 8 or 9, characterized in that the obtained glycerin has a purity greater than 90%.