WO2010075616A1

WO2010075616A1 - Process for purifying light-coloured glycerol from biodiesel transesterification

Info

Publication number: WO2010075616A1
Application number: PCT/BR2009/000436
Authority: WO
Inventors: Rogério DA CONCEIÇÃO RODRIGUES; Alexandre Dos Santos Machado; Alessander Acacio Ferro
Original assignee: Serviço Nacional De Aprendizagem Industrial-Senai/Dr-Ba
Priority date: 2009-01-05
Filing date: 2009-12-28
Publication date: 2010-07-08
Also published as: BRPI0902550B1; BRPI0902550A2

Abstract

The present invention describes a convenient method for purifying light-coloured glycerol from biodiesel production, without low-pressure distillation and without the need to neutralise the medium by means of chemicals classified as organic or inorganic bases. In the present purification process, acetals and cetals are produced by cyclisation of the respective triol in the presence of various aldehydes and ketones, and in the absence of additional acid catalysts. The cyclised addition products are hydrolysed in various concentrations of distilled water, yielding glycerol with a high degree of purity ranging from 90 to 99.9%, besides a quantitative chemical yield.

Description

BLOND GLYCERIN PURIFICATION PROCESS, FROM BIODIESEL TRANSESTERIFICATION

Field of Invention

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 chemicals 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 in excellent yields.

Background of the Invention

Most of the energy consumed in the world comes from oil, coal 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 paramount importance. This constant search resulted in the discovery of the potential demonstrated by biomass that appears as an alternative source that aims to solve the world energy problem.

Energy generated by biomass can be defined as that supplied by materials of plant origin or obtained by decomposing waste. Brazil has been seeking to use biomass as a renewable source of energy, among which are: firewood, babassu, vegetable oils, vegetable waste, sisal, biogas, rice husk, sugarcane - sugar (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. This possibility of using biofuels of plant origin is quite attractive in view of the environmental and economic aspects. It has been found, however, that the direct application of vegetable oils to engines is limited due to their physical properties such as ^' their high viscosity, low volatility, polyunsaturated character, acidity' which imply problems in their internal parts. of- engines, in-virtii / a '. in this way the incomplete combustion in order to reduce the ^viscosity' ^gives: raw material, various alternatives have been considered, such ^'cO' mo ^'to ^the' dilution, micro. emulsion using methanol or ethanol, catalytic cracking and transesterification with ethanol or methanol, promoting the production of biodiesel, according to the reaction below:

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

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 petrochemical naphtha in the production of plastics and other chemical derivatives of higher added value. In the scientific literature, information was found ^'that the share of biodiesel in the energy matrix of Brazil tends to rise from 3% in 2008, called B3, to 5%. in 2013 (B5), ^' with prospects for these indices to increase until B20 in 2020.

Growing concern about global warming encourages discussions worldwide about new, less polluting energy sources. ^' Modern society is increasingly dependent on oil, but the viability of renewable fuels, which would have a much lesser impact on global warming, is already being discussed, as the overall balance reduces CO ₂ emissions, one of the main villains of the greenhouse effect. greenhouse.

There are still some vagueness of what biodiesel is, and can be considered a mixture of vegetable oils and diesel, or can 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 from the transesterification of vegetable oils used in frying, domestic or industrial sewage.

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

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

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

With the introduction of biodiesel in the market, around 800,000 tons of glycerin were traded worldwide in 2005, according to Pagliaro in his article titled "From Glycerol to Value-Added Products." The forecast for Brazil indicates that there will be a production of 120 thousand tons per year of glycerine with the entry of B3 and 200 thousand 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 have If successful, it is important to investigate economically viable solutions for glycerine purification in order to. enter it again in the chemical çadeiá'- ^'' as a raw material with higher added value, since. The price of this product is grossly lower. ·

For purification of. glycerin ,, two methods described in the literature are the; most commonly used .. These methods are. known as -converibfone process' - e. "ion exchange" and are the most used by industries. . However, they present serious problems.

The conventional process is the addition of HCl and the SFIC ₃ crude glycerin in order to maintain the pH between 4 and 4.5, in order to remove ^soaps' and other organic impurities. Then the fatty acids formed are filtered off and the filtrate is neutralized with NaOH to pH 6.5. Once ^'this treatment, the crude glycerol contains water, NaCl, methanol and other organic waste materials. The filtrate is then evaporated to 80 to 90% glycerine (by mass).

This procedure is an adaptation of US Patent No. 4655879 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 mm Hg in the second stage), which makes glycerin degradation above 200 ° C difficult.

During water evaporation it is inevitable to concentrate inorganic salts that begin to crystallize and therefore need to be continuously removed from the system through the evaporator bottom to prevent scale in the equipment. Then the recovered glycerin is brought to a centrifuge. The remainder of dissolved salt is sedimented in ^tanks' for six hours to conical 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 ° ρ, distillation should always be performed at reduced.

In the process involving ionic resins, crude glycerin is treated similarly to the conventional process until the neutralized filtrate is obtained. The purification is then performed 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. It is noteworthy that ion exchange units work efficiently for dilute solutions containing 20 to 40% glycerin. The material is passed through the resin bed (see US Patent No. 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 to give a glycerine of more than 99% purity in the end.

The French patent, FR No. 578306, describes a heterogeneous azeotropic 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 into a condensing steam chamber in perforated plates arranged in a planned distillation column. Although it is a seemingly practical alternative for industrial use, the procedure shows difficulties in reproducibility of the results, since all work is directly linked to process variables such as: glycerin feed (g / s), toluene vapor feed (g / s). s), glycerine feed temperature (° C), initial glycerine concentration (mass%), glycerine outlet concentration, and 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 cyclization with aldehydes and ketones containing from 1 to 4 carbon atoms. The products obtained, called acetals and ketals, are separated at elevated temperatures, lyi _. esmp: presenting lower boiling point 'than own ^' ppjióis.,. the water is still -. one: factor limitatitis; stop ^'this pr cess. 0 ^:: - ^: matè iàí · .. ■ recovered, is submitted to one. reactor where. the reaction occurs ^: d ^' e _. hidr ^' o¾sê ^' ;: ^' na ^! 5 ·, ... pre-de-alreadys .njuals .or. ion exchange resins Other- · 'ΐ¾¾ ^' ^ ^' ό · ·. - similar ,; _: ao.

It can be found in ^'r ^PAT' ^{ehtë; t} .francesa ir.RN 83360.7 ^0,.

U.S. Patent US N ° 5527974, describes a purification process ^'for .glicerina obtained .partir • high pressure hydrogenation (bar 100 ^is' 10 ^• · temperatures of 100 ° to 250 ° C) natural fats .envolvendo . After hydrogenate the fat, a.glicerina cpnténdo ^'traces of fatty acids and other impurities are forced to pass through a column containing a membrane that simulates • microfiltration. The process is inefficient as clogging problems are frequent. throughout the operation.

15 Summary of the Invention

It is an object of the present invention to describe a process of purifying glycerine .loura, derived from the production of biodiesel -, which comprises two distinct steps without the need for reduced pressure distillation and complete recovery of carbonylated agents. The reaction that was the basis for the studies developed is the glycerine acetalization and / or ketalization reaction using different ketones and aldehydes. It is noteworthy that the documents found in patent literature do not preclude ^'the studies of their ·, invention, serving only as support for the development of a process of easy handling, reproducible, fast and low cost 25.

Description of the Figures. .

·. Figure 1 shows the chromatogram for the follow - up of. reaction-.;. in . ketal hydrolysis. glycerine derivative of blond amount ^'■ .... equimolar in distilled water. 5-minute time intervals, 30 minutes,. 30 ·. q 75 minutes. Figure 2 shows the chromatogram for the cyclohexanone-derived ketal.

Figures 3 and 4 show the infrared spectra for glycerin PA and blonde glycerin after being treated according to the procedure described in this invention.

Detailed Description of the Invention

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

G _{| icerjna Pure}

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, and glycerin generated from blends. The different glycerin samples investigated presented high fatty acid content, traces of catalysts and alcohols.

The cyclization reaction involving the different ketones and aldehydes occurred at temperatures ranging from 25 to 100 ° C, under open system stirring without the need for the addition of an acid catalyst as glycerine samples already had sufficient acidity (pH ~ 1.0 ) for the reaction to occur, even partially, at room temperature. This reaction 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 ratio between 1.0 is 3.0.

molar ^{"^'rifais"} -Suitable .fSfáró-i OS' 1, W and I: i2 ^'Ú ^\' in ^{^tõcíò's:} The samples studied, - the ternpb. ^" -.da ^• tation 7 ^ ⁵ and ^ déU'W ^' minutes.- The best range is between ^' - 5 and ^' 4 ^: § ^' ~ ^; · - inut s ^ ^'1 ·' · '- ^'''·^''^''

. ^' ··· ^' - ^■ Betting; '^;' -¾ ^{: '} . ^; : Cpnstà {action gone ^' "^" tèrmíhõ ^ - ^'' reaction - ^' - por ^'' (3C S (Gâ's ^{; ''} 'chromátõ, grkphy-mass ^' spéetr ^' omè ^' try) ^' , ^'' oè Cyclic interniédiers were ^' diluídos- ^"with a quantity p and q and h tie acetone and filtered to complete removal of precipitated impurities along ^'the reaction, concentrated and put to hydrolyze ^to" equírriolares amounts of distilled AGLIA in a ratio ranging from 1, O to 3.0 . The temperature range ^'used is between 50 and 90 ° C. The time period for complete cleavage of cyclic intermediates did not exceed .120 minutes. The recovered clear solution of glycerin was set to stir in the presence of activated charcoal and / or diatomaceous earth for a period of the minutes and then filtered. After filtration, the ^'material is placed in an evaporator route, being possible to recover the ketone or aldehyde when they had a low boiling point. glycerin was recovered in st feeds 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 attached. The system was put in a silicon oil bath with the temperature adjusted in a range ^'40-60 ° C. Then, the system was charged ran ^2,00Ó, g (21 74 mmol) of blond glycerin (pH ^'= Ί .0) and 10 ml acetone - ^PA: remaining under agitation for a period of time ranged from 5 to ^'20 minutbs. Acceleration of the reaction by gas chromatography revealed a single product derived from the cyclization. ^' After ^' the ^' realization of the total consumption ^' of the starting material, the acidity has been monitored ^' and ^' pH ~ 5.0. In the first few 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 at 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. After finding the total consumption of the starting material, the solution was treated with activated charcoal and stirred for an additional 10 minutes. The solution was then filtered and concentrated to give 99.9% purity glycerine with quantitative chemical yield. Figure 1 shows the chromatograms for ketal and glycerin after hydrolysis is completed. In Figure 3, it is possible to observe the infrared spectrum of glycerin PA being compared to the infrared spectrum 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 attached. The system was placed in a silicone 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 = .0) and 2.240 g (22.82 mmol) or 2.36 mL of cyclohexanone, while stirring for a period of time. which ranged from 10 to 30 minutes. Monitoring of the reaction by gas chromatography revealed two isomeric products derived from cyclization. After the finding of consumption total material of. match; the acidity was. monitored and pH ~ 4.5. Logo us •. ^• first? ^: minut ^' os. ^' from ^' v'reation-,;. hi .. ^'possjyel' observe ^{^{'Vprecipitáçád'}} - ^{^'das'} 1 ^(JH3 ^s ^^ ': Ponti i3s ^^ <.gllQ¾ ín¾ lp.Mri¾ S0nd &^{faejlrRéhte..'} removed ^{^'AWA;} é¾ ^"; d¾ ^r' ^• .má ^{; '} -swples .filj3¾¾âa5.-A-50lvção .d.çt. ^' Clear ^' characterist ^' ^' was concecated: -çjâadp, originated from .a Oil-with quantitative yield. ^"■'

·: 0 màteniak red¾perado: was transferred to. one. ^' corrected ^' ^' ^' two-necked flask • capacity-par -50, ^' · mliV ^' aÇQpladp> to a condenser for reflux. O ^'' sisi'ma ^':; ' was put: in a silicone oil-bath .com the set temperature ^'W ° C and the medium with .tratado .-. l Joo 1, 30 equivalent of distilled water, remaining constant agitation by an under-> period 95-20 minutes. After the observation of the consumption total starting material, the solution was ^* ^■ treated -with coal -enabled, remaining under agitation for a ^time: add) 30 minutes / Thereafter, the solution was filtered and concentrated to give the com- purity glycerin 95% and quantitative chemical yield;

Example 3

. In a 50 mL two-necked flask, a reflux condenser was attached. The system was placed in a silicone oil bath with the temperature set within a range of 90 - 100 ° C. Then, the system was loaded with 2.000 g (2.74 mmol) of blonde glycerin (pH = 0.0) and 1.872 g (2-1.74 mmol). or 2.32 mL of 3-methyl-2-butanone, remaining under stirring 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. From the starting material, the acidity was monitored and the pH ~ -5.0. Soon ^: rivers ^' first minutes. in ; reaction,. Could - watch ^'· precipitation. ^'• impur.ezas..contidas- of roa blond ,, glycerin is easily removed by means of ^' a ^'.simples, filtration, - .The solution was concentrated feature of ^clear,' d ing origin. _: a'um-óJeó with quantitative yield.

- · · ..: <3 recovered material was ..transferred to 'a two-necked cdm balloon · 50 ml capacity coupled to a reflux condenser. The system was placed in a silicone oil bath with the temperature set at 80 ° C and the medium treated with 1.10 to 1.40 equivalent of distilled water, remaining under constant agitation for a period of 30-80 minutes. After finding the total consumption of the starting material, the solution was treated with activated charcoal and stirred for an additional 15 minutes. Then the solution was filtered and concentrated to give 90% purity glycerin with quantitative chemical yield.

Example 4

In a 50 mL two-necked flask, a reflux condenser was attached. The system was placed in a silicone 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 time period ranging from 30 to 40 minutes. Monitoring of 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 ~ 4.0. In the first few minutes of the reaction, it was possible to observe the precipitation of the impurities contained in the blond 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 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. After finding the total consumption of the starting material, the solution was treated with activated charcoal and stirred for a while. additional 30 minutes. Then, the solution was filtered and concentrated to give ^'a' glycerine with a purity of 93% and yield chimeric ^ ^'' ^{'q¾ántit'atív} ^{^"Ov"' i;} - In a 'balloon burners capable of 50 mL was acopiadó ^{'dm: e} óondensadòr ara reflux The system was put in a bath at &^{oil.':'ãííitórtô} of ^- cO ^f>' will "iêrft> and adjusted átufà ^'a' range 30-45 ° C. In sè'gu ^'round, O sisièmá was charged ^with' 2.000 g (21 74 mmol) of blond glycerin (pH ^'= Ί, 0) and ^"1, 43 g ^(32.61: mmol) or 1, 83 mL of acetaldehyde while remaining under agitation. for a period of time ranging from 50 to 70 minutes. The monitoring of the reaction ^"by gas chromatography revealed two isomeric products from the cyclization derivatives. After finding the total consumption of the starting material, the acidity was monitored and H ~ 5.0. In the first few ^minutes' reaction was It is possible to observe the precipitation of the impurities contained in the blonde glycerin, which are easily removed by simple filtration The clear solution was concentrated to give an oil of quantitative yield.

The recovered material was transferred to a 50 mL two-necked flask coupled to a reflux condenser. The system was put in a silicon oil bath with the temperature set to ^'75 ° C and the ^medium' treated with 1 equivalent of from 05 to 1.20 distilled water remaining under constant agitation for a period of 60 to 80 minutes . After finding the total consumption of starting material the solution was treated with activated carbon, remaining under agitation by a ^{'tempoadicional} 20 minutes. The solution was then filtered and concentrated to give 97% purity glycerine with quantitative chemical yield.

Claims

1) Purification process of blond glycerin, derived from biodiesel transesterification, characterized by the following steps:

a) reacting blonde glycerin with a cyclization reagent under constant agitation at 25 to 100 ° C in an open system without the addition of a catalyst;

b) after completion of step a) dilute the cyclic intermediates with acetone;

c) filtering the cyclic intermediates to remove precipitated impurities throughout the reaction step;

d) hydrolyzing the material which was filtered in step c) thus obtaining a clear solution;

e) stirring the solution obtained in d) in the presence of active charcoal and / or diatomaceous earth 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 glycerin.

Process according to claim, characterized in that the blonde glycerin comes from soybean oil, palm oil, sunflower oil, canola oil, jatropha oil, cottonseed oil, tallow, sunflower, babassu, turnip fodder, coconut, rapeseed, among other oilseeds, or from transesterification 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, 1.10 and 1.20.

6) .. Prpcéssòv.de .acordo with the reivindicação.1 ,, characterized in fãtd ^" to </ step time) does not exceed 60 ^minutes;;

7) Process; according to claim 1, characterized in that the reason is _: between the filtered material in the. stage. c.) .. and water stretching in the range of .1,0.

- .a ¾Q.

·. $) -.Process:, of. according to claim _1: characterized in that ^'• the temperature during step d) remain in the range 50 to 90 ° C and the time interval for complete hydrolysis does not exceed 120 minutes.

A process according to any one of claims 1, 2, 3, 4,

5, 6, 7 or 8, characterized in that the glycerine recovery process has a yield 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 glycerin obtained has a degree of purity above 90%.