Biolubricants: Raw materials,chemical modifications and environmental benefits

The depletion of the world's crude oil reserve, increasing crude oil prices, and issues related to conservation have brought about renewed interest in the use of bio‐based materials. Emphasis on the development of renewable, biodegradable, and environmentally friendly industrial fluids, such as lubricants, has resulted in the widespread use of natural oils and fats for non‐edible purposes. In this study, we have reviewed the available literature and recently published data related to bio‐based raw materials and the chemical modifications of raw materials. Additionally, we have analyzed the impacts and benefits of the use of bio‐based raw materials as functional fluids or biolubricants. The term biolubricants applies to all lubricants, which are both rapidly biodegradable and non‐toxic to humans and other living organisms, especially in aquatic environments. Biodegradability provides an indication of the persistence of the substance in the environment and is the yardstick for assessing the eco‐friendliness of substances. Scientists are discovering economical and safe ways to improve the properties of biolubricants, such as increasing their poor oxidative stability and decreasing high pour points. “Green” biolubricants must be used for all applications where there is an environmental risk.     

Chemical modification of vegetable oils for lubricant applications

Owing to the unfavorable impact on the environment of mineral oil-based lubricants, there has been a steady increase in the demand for biodegradable, environment-friendly lubricants. However, development of a biodegradable base fluid that could replace or partially substitute conventional mineral oil is a big challenge. Vegetable oils are recognized as rapidly biodegradable and are thus promising candidates as base fluids in environment-friendly lubricants. Vegetble oils have excellent lubricity, but poor oxidation and low-temeprature stability. This paper presents a series of structural modifications of vegetable oils using anhydrides of different chain lengths. The reaction was monitored and products were confirmed by NMR, FTIR, gel permeation chromatography, and thermogravimetric analysis (TGA). Experimental conditions were optimized for research quantity and for laboratory scale-up (up to 4 lb=1.8 kg). The thermo-oxidation stability of these new lubricant base fluids was tested using pressure differential scanning calorimetry and TGA. The chemically modified base fluids exhibit superior oxidation stability in comparison with unmodified vegetable oils. These base fluids in combination with suitable additives exhibit equivalent oxidation stability compared with mineral oil-based formulations.     

A study of the oxidation and wear properties of vegetable oils: Soybean oil without additives

The use of biodegradable lubricants in diverse applications continues to increase. Vegetable oils (e.g., soybean oil) are the main biodegradable lubricant base stocks used world-wide. However, there are concerns about their oxidative stability and low-temperature performance. Improvements in oxidative stability can be made through chemical or genetic modifications. This work compared the effects of oils with different chemical compositions. Soybean oil, high-oleic soybean oil, and epoxidized soybean oil were compared in laboratory bench tests. The tests conducted include the Penn State sequential four-ball wear test and the Penn State micro-oxidation test. Oxidation products from the micro-oxidation test were analyzed by FTIR and gel permeation chromatography. In this paper, all oils were evaluated neat, without additives.     

Möglichkeiten der Fettchemie für die Schmiermittelindustrie

Feasibilities of the Fat Chemistry for the Lubricant Industry Animal and vegetable fats and oils have been used for centuries as lubricants. Only the industrialization and motorization led to an immense increase of the consumption of the lubricants which amount today about 1.3 million tons a year only in the Federal Republic of Germany. The mineral oil represents now the most important raw material. Therefore the question arises what contribution the fat chemistry can give today for the lubricant industry to accomplish its various tasks. Feasibilities of the fat chemistry to refine oils and fats furtheron to suitable formulation components for the lubricant industry are pointed out. Thereby actual problems and development tendencies are discussed, which are correlated with the matter of lubricants and are nowadays generally discussed.     

Development of Fully Bio‐Based Lubricants from Agro‐Industrial Residues under Environmentally Friendly Processes

Biolubricants are becoming interesting alternatives to mineral lubricants. Despite their advantages, development of lubricants from vegetable oils may compete with food production, turning their use impractical due to socio‐economic aspects. Here, cardanol is used as raw material in the synthesis of novel biolubricants under environmentally friendly conditions. These compounds are characterized by NMR and Fourier transform infrared spectroscopy. Thermal‐oxidative studies show the elevated stability and higher onset oxidative temperatures. Tribological analyses performed under high‐frequency linear‐oscillation motion indicate lower coefficients of friction and wear rates compared to a synthetic oil. Therefore, cardanol, under simple, fast, and sustainable processes can be transformed into valuable alternatives for petroleum‐based lubricants. Practical Applications: The novel cardanol‐based biolubricants presented in this work show interesting chemical and lubricity properties superior to standard synthetic oils, which make them potential substitutes for the current oil‐based products used as lubricants. Additionally, the ecofriendly methodologies employed reduce significantly the reaction time as well as eliminating the need for catalysts or solvents, making these processes viable alternatives for the traditional methods reported in literature for the synthesis of this class of compounds.     

Trends in industrial markets for fats and oils and derivatives

During the past decade, research by industry and government has developed numerous new chemical markets for fats and oils derivatives. Lower prices for competitive raw materials have forced some of these new products into specialty markets. Economic factors, such as the continual growth of the chemical industry, population increases, and high consumer demand, have allowed for steady growth in the fat-derivative market. New fat-type plasticizers are currently consuming about 60 million pounds of fats annually. Synthetic lubricants will probably be consuming 20 million pounds of fatty diesters annually by 1965. Animal feeds consume approximately 600 million pounds of fats and fat derivatives annually and may eventually become the leading domestic nonfood market for fats. The protective coating market as an outlet for fats continues to decline, and the continuing shift to nonfat materials and changes in pain formulas indicate that, while the demand for protective coatings may increase, the use of fats in their manufacture may not share in the increase. Nonfat chemical raw materials provide intense price competition for fatty raw materials. Fat prices are influenced by the demand for use in food, soap, paints, and possibly animal feeds rather than by the demand for use as chemical raw materials. Presented before the American Oil Chemists' Society, New York, October, 17, 1960.     

世界油脂化工市场（英）

油脂化工产品的原料来自于动物性和植物性的油和脂肪,它们也衍生许多化工产品。然而,由于油脂化工产品的独特性质,它主要为肥皂、清洁剂和洗发水等产品提供广泛的表面活性剂原料。通常在制成品前,这些基本的油脂化工产品需进行进一步的转化程序。油脂化学品原料取之天然可再生,可生物降解,而石油原料却无法再生。因此,从这一点来讲油脂化学品对环境更友好。指出油和脂肪的价格变化无常,以及副产品甘油的价格因供求而变是造成油脂化工生产经济不稳定的两大因素。     

Depression of pour points of vegetable oils by blending with diluents used for biodegradable lubricants

Low-temperature properties need improvement before vegetable oils can receive wider recognition as biodegradable lubricants. Effects of dilution with major biodegradable fluids, namely poly alpha olefin (PAO 2), diisodecyl adipate (DIDA), and oleates, as well as impact of pour point depressant (PPD), were investigated. Since solidification of mixed unsaturated triacylglycerols is a complex thermodynamic process, the study was limited to pour point determinations. Vegetable oils demonstrated higher pour points with increased saturation and molecular weight. Cis unsaturation and hydroxy groups favored lower pour points. Dilution with oleates appeared less effective than dilution with PAO 2 and DIDA. Addition of 1% PPD (w/w) depressed pour points down to −33°C for canola and −24°C for high-oleic sunflower oils. However, neither higher amounts of PPD nor incorporation of diluent produced further depression. Depression of pour points was not proportional to the amount of diluent and ceased with further dilution. Low-temperature performance of vegetable oils limits their prospect as biodegradable lubricants, but well-balanced usage of PPD and diluents can deliver some improvements.     

油脂环氧化的研究进展

环氧化油脂用作可循环再生的生物降解材料、无毒润滑油、高聚物稳定剂和各种中间体等,是良好的增塑剂。介绍了各种油脂环氧化的制备方法、研究现状和应用情况,以及未来的发展前景。目前应用最广泛的制备方法是用过氧化物环氧化油脂中的双键,使其成为环氧乙烷的形式,而环氧油脂的各种性质主要因为其中的环氧键的存在。     

Synthesis and Characterization of Potential Bio-Based Lubricant Basestocks via Epoxidation Process

Chemical modifications of vegetable oils may be applied for the purpose of improving their physicochemical properties in their usage for the bio-based lubricants. The vegetable oils with a high percentage of oleic acid, such as soybeans and rapeseed oils, are important raw materials to obtain the biolubricants. In this particular study, the oleic acid was esterified with 1-octanol, followed by epoxidation. The oxirane ring opening reaction was performed using different alcohol structures (linear, branched, and cyclic), in order to evaluate their influence on the final physicochemical properties with the synthesized samples. These aforesaid reaction steps were followed by ¹H nuclear magnetic resonance and the main physicochemical properties in the intermediate and final samples were assessed. The highest oxidative stability was observed for the samples obtained, using a cyclic alcohol at the oxirane ring opening reaction (230 min), followed by the linear alcohols with the branched alcohol presenting the lowest oxidative stability (124 min). The pour point values for the samples synthesized with the branched alcohol were slightly better than those with the linear and cyclic alcohols. All the synthesized samples showed high viscosity indexes (>130) and kinematic viscosities at 40 °C, ranging from 30 to 33 cSt (application degree ISO VG-32), which are adequate for their use in the formulation of bio-based lubricants.     

Basestock Oils for Lubricants from Mixtures of Corn Oil and Synthetic Diesters

Environmentally friendly vegetable oils and their derivatives represent alternatives to mineral-based lubricants. Vegetable oils have high biodegradability and low production costs. Their poor thermo-oxidative stability and poor low temperature properties are disadvantages in their use as lubricant basestocks. In our study we used corn oil and diester mixtures, which become lubricants when additives are introduced. These mixtures of corn oil and di-2-ethylhexyl-adipate (DOA) and di-2-ethylhexyl-sebacate (DOS) offer a wide range of kinematic viscosities, pour points lower than −39 °C and flash points over 218 °C. The diameters of wear scars measured under four-ball testing (40 daN) are less than 0.90 mm and the copper strip corrosion test result is 1a. The differential scanning calorimetry study and thermogravimetric study under nitrogen atmosphere and in synthetic air are reported. From these studies a higher thermal stability was observed for corn oil than for diester oils. The thermo-oxidative instability occurred at temperatures higher than 350 °C. The low production cost of corn oil and its mixtures with diesters makes them an attractive alternative to mineral oil lubricants.     

Development of mineral oil free offset printing ink using vegetable oil esters

Until the middle of this century, fats and oils are the major raw material source for paints, coating and lubricating applications. These markets are completely taken over by petroleum based stocks due to their abundance and versatility. However, recent public awareness to use environmentally acceptable products that minimize pollution, are compatible to human health and readily biodegradable created opportunities for vegetable oils for application in paints and printing inks. The formulation of vegetable oil methyl ester based 'green' offset printing ink that reduces the volatile organic compounds (VOC) has been discussed in the present study. Methyl esters of rapeseed, soybean, rice bran and palm oil have been prepared and their physical properties have been measured and compared with standard petroleum feed stock. Varnishes were prepared with these esters and their properties are also compared with that of the petroleum based products. Rheological properties of the inks are also evaluated and compared with standard printing ink using petroleum based solvent. In general performance of the ester-based printing inks are comparable with that of the mineral oil based product. On the basis of tack stability and gloss, ester based inks are much superior than the mineral oil based products. In conclusion, a new non-volatile diluent for printing ink has been developed. The diluent is made from common vegetable oils like rapeseed, soybean, rice bran and palm oil, a renewable source that is environmental friendly. Vegetable oil esters offer a cost effective solution for mineral oil based printing ink to meet VOCs regulations.     

Modified Triglyceride Oil Through Reactions with Phenyltriazolinedione

Most of the current lubricants originate from petroleum stock, which may make them difficult to dispose of and be environmentally unfriendly. Triglyceride oils are good platforms for new products that can substitute for conventional mineral oil-based lubricating oils and synthetic esters. As part of the effort to develop new uses of triglyceride oils, a modified triglyceride oil was synthesized through the reactions with 4-phenyl-1,2-4-triazoline-3,5-dione (PTAD). The process required no solvent or catalyst and entailed only the mixing of triglyceride and PTAD. ¹H NMR was used for structure determination and to monitor the reactions. Several reaction products were produced, and their relative yields depended on the stoichiometry and temperature of the reaction. The reaction product mixture exhibited a self-curing behavior as a function of time. Thus, the viscosity of a mixture containing PTAD and triglyceride in a 3:10 weight ratio increased 40-fold in about 2 h at room temperature, suggesting its possible use as an additive in lubricants, caulking, cement and thickener applications.     

Crossroads

Summary The publicity on water contamination by detergent foams is awakening the public to the growing problems of air, water and soil pollution by all types of waste materials. While detergents account for only 5–10% of total dissolved organic matter after conventional sewage treatment, their foaming tendency highlights their presence. Legislative action therefore seems inevitable. The branched-chain alkylbenzene sulfonates and the branched-chain alkylphenol polyglycol ethers are generally considered unsatisfactory from the standpoint of biodegradability. Straight-chain alkylbenzene sulfonates are biodegradable, though tests to date indicate the rate of degradation is much slower than that of the fatty alcohol sulfates. In general, the lower molecular weight species of each detergent type produces more foam on agitation, but degrades more rapidly than the higher molecular weight species. The extensive research work on biodegradables may open new usage potentials for both animal fat and vegetable oil derivatives. It has already led to development of alpha olefins derived from petroleum sources, and unless producers and processors of agricultural fats and oils work equally hard on developing their own derivatives, the petroleum-based raw materials will take over even more than soap’s former detergent market. Right now, the natural fats and oils seem to have a built-in advantage of biodegradability to answer the basic problems of detergent suds and stream pollution     

Dependence of oil stability index of fatty compounds on their structure and concentration and presence of metals

During storage and use, vegetable oil-derived industrial products such as biodiesel and biodegradable lubricants can be subjected to conditions that promote oxidation of their unsaturated components. The materials arising during oxidation and subsequent degradation can seriously impair the quality and performance of such products. Therefore, oxidative stability is a significant issue facing these vegetable oil-derived products, and enhanced understanding of the influence of various components of vegetable oils and storage parameters is necessary. In this work, the oil stability index (OSI) was used for assessing oxidation of monoalkyl esters of FA by varying several parameters. Neat fatty compounds and prepared mixtures thereof were studied for assessing the influence of compound structure and concentration. Small amounts of more highly unsaturated compounds had a disproportionately strong effect on oxidative stability. The recently developed concept of bis-allylic equivalents correlated more closely than the iodine value with the OSI times of mixtures of fatty esters. The OSI times of free acids were shorter than those of the corresponding alkyl esters. The presence of copper, iron, and nickel also reduced oxidative stability, but their effect was less than the presence of more highly unsaturated fatty compounds. Of these metals, copper had the strongest catalytic effect on OSI time. OSI may be an alternative to long-term storage tests for determining the influence of extraneous materials such as metals on oxidative stability.     

Perspektiven des Ölpflanzenanbaus aus der Sicht der deutschen Agrarwirtschaft – Voraussetzungen und Forderungen

Prospects in Oil Plant Cropping from the Viewpoint of German Agricultural Economy - Prerequisites and Acquirements The cultivation of oil crops has a longstanding tradition and has so far been concentrated on the production of vegetable oils for human nutrition. Winter rape plays the dominant role in oil plant cropping here. In addition to its applications in the food sector, rapeseed oil as a renewable raw material also has other potential uses. The utilization of rapeseed oil as a raw material in the chemical industry results in high demands being made of rape breeding and its implementation. The pressure caused by the dramatic surplus production in the EC has resulted in the development of greater efforts to utilize the plants in the industrial sector. As a lubricant, rapeseed oil can already hold its own on a commercial basis. The situation in the fuel sector is different. The production of rape methyl ester, the diesel substitute, is still more expensive than diesel fuel itself. For the use of rapeseed oil as a basic material for tenside production, for solvents and additives in the paint industry and as a basic material for the production of plastics additives, the content of a fatty acid must be raised to above 85%. This would represent a great step in the direction of providing tailor-made, industrially-oriented vegetable oils. Breeding efforts must be intensified in this respect, but no short-term results are to be expected here. The prospects for vegetable raw materials on the basis of a price comparison with fossil raw materials are positive, however, if for instance a regulation specifying the admixture of rape fuel oil and rape diesel, a regulation specifying the use of hydraulic oil and rape lubricants were to be introduced and the environment-policy advantages of this were to be evaluated. As environment awareness increases, the discussion concerning the burdens placed on the atmosphere becomes more intense. The main subject in this connection is the CO₂ regime in the air. The endeavours to return to closed circuits in energy policy are very much in line with the use of renewable raw materials. Since the problems of oil plant cultivation are of such great economic and social-policy importance, they necessitate vigorous political action at national and EC level.     

Reduction of Free Fatty Acids in Acidic Nonedible Oils by Modified K10 Clay

Biodiesel is a biofuel obtained from vegetable oils. The oils used as raw materials are usually refined edible vegetable oils. Nonedible acidic oils are unsuitable for biodiesel production unless reduction of the high content in free fatty acids (FFA) of these materials had been achieved. Obtaining a good raw material from unprofitable oils becomes an important research field. Additionally clays have a long history in industrial sorption and catalysis, some being commercially available and with properties that can be modified. In this work we present the results of the use of the montmorillonite clay K10 and two acid modified clays K10(I) and K10(II), in the esterification of stearic acid with methanol and 95 % of methyl stearate was obtained with K10(II). These clays were then used for the first time to reduce the acidity of enhanced FFA sunflower oil and they show to be very effective. Reduction of FFA from 11 to 4 % was obtained with K10(II) mainly due to 94 % conversion of FFA into fatty acid methyl esters (FAME). These clays were also tested with two waste oils, one from domestic use and the other gathered from different restaurants, and showed their ability to lower the acidity of these oils. Reactions were followed by ¹H NMR as well as quantitative determination of FFA and FAME. Clays were characterized by FTIR and XRD.     

Life cycle analysis of biodiesel production

Biodiesel has attracted considerable attention as a renewable, biodegradable, and nontoxic fuel and can contribute to solving the energy problems, significantly reducing the emission of gases which cause global warming.The first stage of this work was to simulate different alternative processes for producing biodiesel. The method used for the production of biodiesel is the transesterification of vegetable oils with an alcohol in the presence of a catalyst. The raw materials used were palm oils and waste cooking oil.The second stage was a life cycle analysis for all alternatives under study, followed by an economic analysis for the alternatives that present minor impacts and which are more promising from an economic point of view. Finally, we proceeded to compare the different alternatives from both the point of view of life cycle and economic analysis.The feasibility of all processes was proven and the biodiesel obtained had good specifications.From the standpoint of life cycle analysis, the best alternative was the process of alkaline catalysis with acid pre-treatment for waste cooking oil.The economic analysis was done to the previous mentioned process and to the process that uses raw virgin oils, methanol, and sodium hydroxide. This process has lower investment costs but the process of alkaline catalysis with acid pre-treatment, whose main raw material is waste oil, is much more profitable and has less environmental impacts.     

乙烯复分解反应在生物质合成烯烃化学品中的研究进展

通过乙烯复分解反应,将生物质原料中的双键切断,获得端烯化学品,为实现生物质原料制备高附加值化学品开辟了广阔的前景。本文围绕乙烯复分解反应在生物质原料的应用,简述了该反应的机理和发展,介绍了乙烯复分解催化剂,阐述了乙烯复分解反应在油脂、腰果壳油、巴豆酸酯、苯丙氨酸等生物质原料合成中的研究进展,这些反应得到的端烯化学品可用于润滑剂、聚合物、香料、药物中间体等领域,其中在微波辅助下油脂乙烯复分解反应周转数最高可达1561500,有望工业化,同时指出乙烯复分解反应存在催化剂价格偏贵且难以回收、部分生物质原料转化率和产率偏低的问题,建议接下来的研究除了开发更加经济且高效的催化剂外,还应探索合适工业化的原料、催化体系和工艺过程。     

Fats and oils as chemical intermediates: Present and future uses

Currently, fats and oils possess about 40% of the paint binder, 50% of the surfactant, and 15% of the plasticizer markets. Other markets considered here, with estimated fats and oils percent share of these markets in parentheses, are: adhesives (1%), Agrichemicals (10%), engineering thermoplastics (2%) and synthetic lubricants (20%). With the expected growth for these markets and with fats and oils retaining the same percent share, an additional 3000 million pounds of fats and oils would be needed in 1990. In the likely event that the fats and oils share is accelerated, an additional 7500 million pounds would be required. These requirements could be met by an additional 10 or 25 million acres of soybean production, respectively, which can be easily attained by U.S. agriculture or by diversion of other crops or animal fats from edible use or export.