BR102013033582A2 - Production process of castor oil-derived biolubricants with homogeneous tin-based catalyst - Google Patents

Abstract

The process of producing castor oil-derived biolubricants with homogeneous tin-based catalyst The main object of the present invention is to provide a process of producing castor oil biolubricant from the transesterification of methyl ricinoleate (castor oil biodiesel) with the trimethylolpropane alcohol (tmp) using tin dibutyldilaurate (dbtdl) as the homogeneous catalyst. As advantages of the processes are developed in the present invention using the homogeneous catalyst dbtdl in tmp in the methyl ricinoleate transesterification reaction, it is emphasized that it generates a small amount of residue (methanol), using low severity operating conditions; present high reaction yield, simplicity and low cost when compared to conventional routes in the production of biolubricants.

Description

PRODUCTION PROCESS OF CASH OIL DERIVED BIOLUBRICANTS WITH A HOMOGENIC CATALYZER BASED ON

TIN

FIELD OF THE INVENTION The present invention relates to a process of producing castor bean biolubricant by transesterification of methionic ncinoleate (castor oil biodiols) with trimethylethylpropane alcohol (TMP) using as a homogeneous catalyst, dibutyldilaurate. tin (DBTDL).

BACKGROUND OF THE INVENTION

In the last decade there has been a worldwide concern about the environmental impact resulting from the use of petroleum products. Although only about 1% of all oil consumed is used in the formulation of lubricants, most of these products are disposed of in the environment without any treatment. Some of these hydrocarbons are carcinogenic and resistant to biodegradation, posing a serious threat to the environment.

In this scenario, there is a concern on the part of oil and energy companies to develop biodegradable lubricants.

Lubricants, depending on their applicability, must exhibit certain physicochemical properties within certain specifications, such as viscosity. acidity index, corrosivity and pour point. In the case of biolubricants, usually represented by organic esters, oxidative stability. Thermal and hydroSitic are fundamental, being the first one of the most important properties in the development of a biodegradable lubricant.

However, as a highly oxidation-resistant molecule is synthesized, with double bonds removed or protected by steric hindrances, it should be borne in mind that the action of the microorganisms responsible for the biodegradation will be hampered. In this context, the major challenge in the formulation of bioubricants is to find a molecule that has high oxidative resistance and is biodegradable. The polluting potential of mineral oil is extremely worrying. It is estimated that 1 liter of mineral oil is capable of taking 1 million liters of fresh water unfit for consumption. In the case of two-stroke engines, the main current application of bio-lubricants, the lubrication mechanism results in the release of unburned oil along with the exhaust gas, creating the possibility of environmental pollution.

In particular, when marine engines are used in rivers, lakes or oceans, unburned oil in the exhaust gas is released into the water and may cause pollution in it. In addition, tractors, agricultural machinery, chainsaws and other forestry equipment can also pollute forests and rivers due to sparingly burnt oil, which is released.

Therefore, measures to reduce the impact on the environment should be adopted. In general, the preservation of the environment is due to the intervention of the following driving forces: environmental disasters, public awareness, government guidelines and regulations, globalization of markets and economic incentives.

For lubricants, it is possible to replace mineral oils with biodegradable synthetic lubricants.

A promising alternative for replacing lubricants of mineral origin is the use of esters of some fatty acids derived from vegetable oils which are biodegradable and may have feasible characteristics when compared to mineral oils such as pour point. viscosity, viscosity index and oxidative stability.

When it comes to the use of vegetable oils, it is well known that sunflower and canola oils predominate in Europe, which are glycerine esters and long chain fatty acids (triglycerides). In Brazil, the oilseeds that deserve special mention are soy and castor beans. Fatty acids found in natural vegetable oils differ in chain size and number of double bonds. Natural triglycerides are rapidly biodegradable and quite efficient as lubricants, however, have limitations as to thermal, hydroxy and oxidative stability.

In this context, pure vegetable oils are only used in applications with low thermal requirements such as demoulding and chainsaw oils.

The disadvantages of using vegetable oils as biolubricants can be overcome by the use of additives, but biodegradability, toxicity and price are compromised. An alternative to improve the quality and broaden the applicability of vegetable oil as biolubricant is to perform molecular modifications through organic synthesis, using both homogeneous and heterogeneous catalysis. Castor bean (Ricinus communis) or castor is a shrub whose fruit is extracted from an oil of excellent properties, of wide industrial applicability. Castor oil has been known since ancient times for its medicinal properties and as a lightening oil. In the twentieth century. However, pharmacopoeia is no longer useful, and the major consumers today are the chemical and lubricant industries. Castor oil, or "Castor Oif." As it is known internationally, has unique physicochemical properties such as density, viscosity, alcohol solubility and lubricity superior to all vegetable oils. Castor oil can be used in synthesis routes. for a wide variety of products From this oil it is possible to obtain the biodiese which replaces petroleum-derived diesel oil.

Moreover, this oil has in its composition ricinoleic acid (90%), which has the peculiarity of having a hydroxy in carbon 12, and has a double bond strategically positioned in carbon 9 of its chain of 18 carbons. Ricinoleic acid is an 18-carbon hydroxy acid containing an unsaturation of configuration useful in carbons 9 and 10. Direct use of castor oil or its hydrolysis products as biolubricant is not technically feasible due to Low oxidative stability, high acidity and low viscosity index. Lubricating products must have high oxidative stability and low pour point, characteristics that are generally not easily found in plant based products.

Given the above, castor oil stands out due to the fact that it is the densest and most viscous vegetable oil commonly known, and can reach a viscosity 10 times higher than sunflower oil, presenting a good applicability within the chemical industry, since it has 30% higher lubricity power than the other oils investigated.

Products derived from castor oil have interesting physicochemical properties for lubricant formulation. However, some of the processes described in the prior art using it have some disadvantages with respect to the present invention. US8410G33, published March 1, 2012, discloses a method of preparing diester-based compositions for the formulation of biolubricants, which are prepared by reacting vicinal diol species with one or more monoester. fatty acids.

Monoesters are derived from algal triglycerides. According to the authors, ester-based lubricants in general. exhibit excellent lubrication properties due to the polarity of the ester molecules they are made of. These biolubricants are less volatile than conventional lubricants and are excellent solvents and dispersants. However, depending on the preparation route of these esters, the process may be more expensive and laborious for experimental execution.

Another prior art representative is U.S. Patent US6018063, published January 25, 2000, which describes the ester synthesis of a oleic acid stole with properties suitable for lubricant formulation. That document states that the sterol formed by the use of the invention described herein can be used without additives, which are generally used to improve the quality of the lubricant, which would consequently make said invention advantageous over other biolubricant production routes. Already the previous relative to the article of Salimon, Jumat; Salih, Nadia and Yousef, Emad; "Synthesis and Characterization of esters Derived from Ricinoleic Acid and Evaluation of their Low Property"; Sains Malaysiana 41 (10) (2012): 1239-1244: the study of the chemical modifications made from the epoxidation of ricinoleic acid. The authors found that increasing the size of the ester intermediate chain had a positive influence on the properties of diesters at low temperatures due to the creation of a steric barrier around the molecule, inhibiting crystallization and thus resulting in a low freezing point.

Another invention which describes the production of biolubricants from the transesterification reaction using the enzymatic route is US 6117827, published 12/09/2000. In this document, the end product is a mixture of mono- and di-unsaturated fatty acids of chains in the range of 15 to 16 carbon atoms.

The above documents do not cite or even suggest the use of a specific catalyst, such as DBTDL of the present invention, in the presence of TMP. in the process of obtaining biolubricants from castor oil. The use of tin (IV) complexes, such as DBTDL, as a catalyst in vegetable oil transesterification reactions can be found in some scientific publications. By way of example there is the study by Ferreira, DAC, et al. Entitled "Methanolysis of soybean oil in the presence of (IV) complexes" in Applied Catalysis A: General 317, 58-61. 2007. In that study, It was observed that in soybean oil methanolysis, at different reaction times, temperatures and catalyst quantities, the order of reactivity in terms of fatty acid methyl ester yields was: DBTDL> DBTO> modified dibutyltin oxide> BTA Daniel Ribeiro de Mendonça's Master's Dissertation - Federal University of Alagoas - entitled “Use of tin (IV) catalysts in transesterification reactions: obtaining biodiesef) published in February 2008. investigated the use of organometallic complexes (IV) as catalysts in the aolicolysis of vegetable oils (soybean oil and castor oil) In particular, the catalytic activity of the following tin compounds was investigated. o (IV): BTA, DBTO and DBTDL in said reaction.

In this study, transesterification reactions with different reaction times, vegetable oils, reactor types (glass reactor coupled to a reflux condenser (RVCR) and stainless steel reactor (RP)), and the effect of alcohols (methanol) were reacted. , ethanol, isopropanol, butanol and isobutanol).

For the production of castor oil biodiesei it was found that the best operational option for castor oil methanolysis would be the use of catalysts: - DBTO followed by BTA acid, both reactions operating at 120 ° C and at 2 hours. Compared to soybean oil, castor oil showed lower transesterification activities possibly due to the effect caused by the size of the castor oil fatty acid chain, the degree of oil unsaturation and the interference of the group. hydroxyl in catalyst deactivation. Already in the Master Thesis of Tatiana Maciel Serra - Federal University of Alagoas, entitled: - “Development of tin (I) -based catalysts for the production of methyl fatty acid esters via transesterification and esterification”, published in March The aim of the study was to investigate the catalytic activity of four metal complexes exhibiting Lewis acid character.These studies were directed to: tin dibutyldiacetate, tin dibutyldilaurate, dibutyl tin oxide and butylstanoic acid in the transesterification reactions of soy and castor beans.

One of the conclusions of the study was that for the reaction conditions studied, the yield values (% FAMEs) in soybean methanolysis were higher than those of castor bean methanolysis, and that the catalytic system using RP was more efficient. Moreover, the hydroxyl group present in the C12 of the ricinoleic acid chain may have negatively influenced the reaction yields in castor oil methanolysis (% FAMEs).

Thus, it can be inferred that a process for obtaining castor bean biolubricants from the transesterification of methyl castor oil (castor oil biodiesel) using the homogeneous catalyst, DBTDL has not been described in the prior art. presence of a specific alcohol such as TMP. The present invention has as its main motivation the valorization of biomass as raw material, since there is a worldwide tendency to gradually replace the compounds of fossil origin with those of vegetal origin, highly biodegradable, without harming the environment. Thus, for the lubricant market, biolubricants have become a feasible alternative that is already being used in many European countries through the development of more economical and simple processes.

Clearly, advantages of the processes developed using the homogeneous catalyst DBTDL in TMP in the castor oil biodiesel transesterification reaction are: to generate a small amount of residue (methanol), to use operating conditions with low severity; present high reaction efficiency and simplicity and low cost when compared to conventional routes in the production of biolubricants.

In addition, methyl ricinoleate, obtained from a transesterification reaction of castor oil with methanol, is the main constituent of biodiesel. Thus, the transesterification of this compound with higher alcohols, such as the one employed in the present invention, TMP, has made it possible to obtain polyol esters, these being important precursors of synthetic base oils. SUMMARY OF THE INVENTION The present invention relates to a production process of castor oil-derived biolubricants using DBTDL as a homogeneous catalyst in TMP medium. The production route of castor bean biolubricants used in the present invention was the transesterification of methyl ricinoleate (castor oil biodiesel) with trimethylolpropane alcohol (TMP) using the homogeneous di-butyl tin laurate catalyst (DBTDL). ). This route was very feasible and promising due to: generating a small amount of waste (methanol), using low severity operating conditions; present high reaction yield; simplicity and low cost when compared to conventional routes in bioiubricant production.

Through the processes developed in the present invention, from the use of said homogeneous catalyst, DBTDL in IMF alcoholic medium, it was possible to obtain castor oil-derived bioiubricants with excellent advantages such as: 1) More economical route development and simple for bioiubricant production; castor free biolubricant in its formulation; The biodiesel used does not have to be rigid in its specification; 2) In the castor bean biolubricant production route low cost reagents were used. Yield was 70% pure castor bean biolubricant, free from other components; 3} Use of raw material of plant origin and reagents with low toxicity during the reaction; 4) Tests have shown that the results obtained with castor bean biolubricant in terms of conversion (70%) exceed those obtained by the state of the art (approximately 55%). 5) Production of biodegradable product; the effluents used may be partially returned to the process;

DETAILED DESCRIPTION OF THE INVENTION The process of producing bioiubricants object of the present invention applies to fillers comprising methyl ricinoleate, in particular to castor bean biodiesel.

Broadly, the process involves the transesterification of methate ricinoleate with trimethylolpropane using a homogeneous catalyst, in this case di-butyl tin laurate (DBTDL).

At an initial stage, the charge, comprising methyl ricinoleate, is heated in a reactor at temperatures ranging from 55 to 70 ° C, preferably 60 ° C, under vacuum (absolute pressure between 50 and 150 mmHg), and for a period of time. at least 1 hour. This initial heating step is necessary for the removal of residual moisture from the charge as the presence of water may prevent the hydrolysis of methyl ricinoleate.

After removal of residual moisture from the charge, it is heated in the reactor to a temperature of 165-175 ° C (preferably 170 ° C) under the same pressure condition, then the TMP and then the DBTDL catalyst are added. under agitation ranging from 800 to 1200 rpm. The addition of TMP and catalyst is performed so that the molar ratio between methyl ricinoleate and TMP in the transesterification reaction is 3.2: 1, and the ratio of catalyst mass to methyl ricinoleate mass range from .025% to 0.5%. The reaction time ranges from 5 to 7 h, with the reactor kept under vacuum, absolute pressure ranging from 50 to 150 mmHg. to ensure that all methanol generated in the reaction is removed from the reaction medium, The amount of methane! formed in the reaction depends on its conversion. For a 70% conversion. for example there is. in general a production of 6.3% methanol relative to the total added mass of methyl ricinoleate and TMP.

For the recovery of the biolubricant product, unreacted charge (methyl ricinoleate), and uneaten TMP, two further steps are required: - evaporation to remove TMP and; - molecular distillation to separate methyl ricinoleate from biolubricant.

In this case. Both evaporation and molecular distillation occur with the use of high vacuum, thus having mild temperatures, thus maintaining the integrity of the biolubricant generated, especially with regard to oxidative stability and acidity. In addition, it is possible to reuse unreacted methyl ricinoleate by returning it to the reactor as part of its feed (charge).

For evaporative removal of the TMP 'the stream comprising biolubricant, TMP and unreacted methyl ricinoleate' is passed to an evaporator and subjected to temperatures between 120 ° C to 180 ° C and absolute pressure in the range 0.1 to 0, 4 mmHg.

The entire circuit for TMP recovery must be kept warm, usually at a temperature of 70 ° C, to avoid solidification of the alcohol in the pipes. After removal of the TMP, a stream comprising methyl ricinoleate and biolubricant is routed to a molecular distillation column, operating within the temperature range 190 ° C to 240 ° C, absolute pressure 0.001 to 0.04 mmHg, obtaining a stream containing methyl ricinoleate and a stream containing the biolubricant. The biolubricant obtained according to the process of the present invention has a viscosity at 40 ° C of 290 to 300 cSt, and at 100 ° C of 24.10 cSt, a viscosity index (IV) of 100 to 105, flowability -33 to -39 ° C and total acidity index (IAT) in (mgKOH / g) from 0.30 to 0.50.

EXAMPLES EXAMPLE 1 - Bench scale ethyl ricinoleate transesterification. The bench scale reaction was performed in a 50 ml batch reactor operated glass reactor. The reagents used were ethyl ricinoleate, TMP and DBTDL as reaction catalyst. The reactor was kept under constant stirring (800 rpm) throughout the reaction. The established operating conditions are presented in Table 1.

Table 1. Bench-scale defined operating conditions As a means of ensuring that all generated ethanol is removed from the reaction medium. The reactor operated under vacuum. The ethanol formed was collected with the aid of a dry ice trap. The reaction conversion was 75% (measured with the aid of HPLC) and the final characteristics of the castor bean biolubricant formed in this reaction are shown in Table 2.

Table 2 - Physical and Chemical Properties of the bench cast castor biolubricant * IV: IAT Viscosity Index; Total Acidity Index EXAMPLE 2 - Transesterification of methyl ricinoleate on semi-industrial scale. The semi-industrial scale reaction was conducted in two steps, namely drying of the biodiese! of castor beans and the reaction. In the drying step, the temperature used was 60 ° C for 1h. The reaction temperature was maintained at 170 ° C for 7h under a vacuum of 100 mmHg (0.13 bar) to ensure total removal of methanol generated during the reaction. The stoichiometric relationship of methyl ricinoleate and TMP was the same as used (in example 1). The mass ratio of catalyst to the mass of methyl castolinium used in the reaction is in the range of 0.25% to 0.5%. Table 3 presents the physicochemical characteristics of the castor bean biodiesel and the reaction product formed.

As can be seen from Table 3, the physicochemical properties were strongly changed after the reaction step. The reaction conversion was 73.85%, which is in accordance with what was obtained in example 1.

The divergences between the physicochemical characteristics found in examples 1 and 2 can be explained due to the increased complexity with the increase of the volume produced.

In reaction units, where volumes are smaller, operating variables are easily monitored and controlled, in addition to the fluidic problems caused, which are smaller than in larger volumes. However, comparing the results illustrated in Tables 2 and 3, it is evident that in both cases, the application potential will be the same. The castor bean biolubricant generated in the reaction, without the purification step, could already be used in chainsaws and marine fluids. However, as a way to increase the added value of this compound, this component was purified in a molecular distillation unit.

Table 3. Physical and Chemical Properties of Castor Biolubricant Generated on Semi-Industrial Scale! after the reaction. * Viscosity - ASTM D445 IV: Viscosity Index - ASTM D2270 Fluidity: ASTM D97 IAT: Total Acidity Index - ASTM D664 The reaction product was raw material for the molecular distillation unit. The evaporation step was necessary to ensure total alcohol removal (TMP). After this separation, the biodiesel-bio-lubricant castor oil mixture was conducted to the molecular distillation column for the separation of these products. Separation temperatures in the evaporator and molecular distiller were 160 ° C and 240 ° C respectively. The separation yield of castor bean biolubricant was 70% and its physicochemical properties are shown in Table 4. Table 4 - Physical and Chemical Properties of the purified castor bean biolubricant in the molecular distillation unit. * Viscosity - ASTM D445 IV: Viscosity Index - ASTM D2270 Fluidity: ASTM D97 IAT: Total Acidity Index - ASTM D664 The data presented in Table 4 corroborate the fact that the molecular distillation unit significantly improves physicochemical properties. of the castor bean biolubricant and, consequently, increases the application potential of this product. It is noticed that after the purification step the product was much better than traditionally presented. In addition, the separation yield was high, which makes the process quite promising.

Claims (18)

1. Production process of homogenous catalyst-derived castor oil-derived biolubricants, the tin base, comprising the following steps: (a) providing a charge comprising ethyl ricinoleate to a reactor and heating under vacuum of so as to remove residual moisture from the cargo; (b) Add to the reactor containing the filler trimethylolpropane alcohol (TMP) and a homogeneous tin-based catalyst, under stirring, vacuum and temperature between 168 ° C and 172 ° C, for the time necessary to promote the transesterification reaction of ricinoleate. methyl, to obtain two streams, one stream comprising TMP, unreacted and biolubricating methyl ricinoleate, and one stream containing methanol; e) directing the reactor effluent stream comprising methanol, unreacted methyl biolubricate ricinoleate to an evaporator, operating under vacuum and temperatures between 120 and 180 ° C to remove TMP, obtaining a stream containing unreacted methyl ricinoleate. and biolubricant; f) directing the evaporator effluent stream containing unreacted biolubricant methyl ricinoleate to a molecular distillation column, obtaining a methyl ricinoleate stream and a biolubricant stream. Process according to Claim 1, characterized in that the homogeneous catalyst is tin dibutyldilaurate (DBTDL). Process according to Claim 1, characterized in that the residual moisture is removed from the load at a temperature of 50-70 ° C. Process according to Claim 1, characterized in that the time for removing moisture from the load is at least 1 hour. Process according to Claim 1, 3 or 4, characterized in that the vacuum applied in process steps a) and b) comprises an absolute pressure ranging from 50 to 150mmHg. Process according to Claim 1, characterized in that the transesterification reaction of step (b) preferably takes place at a temperature of 165 to 175 ° C. Process according to Claim 1, characterized in that the transesterification reaction of step (b) has a duration of from 5 to 7 hours. Process according to Claim 1, characterized in that in the esterification reaction of step (b), the molar ratio of methyl castinoleate to TMP is 3.2: 1. Process according to Claim 1, characterized in that in the transesterification reaction of step (b). the mass ratio of the catalyst to the mass of ethyl castinoleate is in the range of 0.25% to 0.5%. Process according to Claim 1, characterized in that the molecular distillation column (e) operates continuously. Process according to Claim 1, characterized in that the evaporator operates at an absolute pressure in the range 0.1 to 0.4 mmHg, Process according to Claim 1, characterized in that the molecular distillation column operates within a temperature range of 190 ° C to 240 ° C. Process according to Claim 1 or 22, characterized in that the molecular distillation column of the step operates in the pressure range from 0.001 to 0.04 mmHg. Biolubricant obtained according to the process described in claim 1; characterized by having a viscosity at 40 ° C of 290 to 300 cSt. Biolubricant according to claim 14, characterized in that it has a viscosity at 10GX of 24.10 cSt, Biolubricant, obtained according to the process described in claim 1, characterized in that it has IR from 100 to 105. Biolubricant, obtained according to the process described in claim 1, characterized in that it has a flowability of -33 to -39 ° C. Biolubricant, obtained according to the process described in claim 1, characterized in that it has an IAT (mgKOH / g) of 0.3 to 0.5.