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Prospectus of Renewable Resources for Lubricant Production

Suruchi Damle and Chandu S. Madankar*

Department of Oils, Oleochemicals and Surfactants Technology, Institute of Chemical Technology, Mumbai, India

Abstract

Lubricants aid in decreasing friction between surfaces in proximity, which in turn lowers the heat produced as the surfaces move. They are composed of 80% to 90% of base oils and 10% to 20% of additives that impart properties like antiwear, corrosion inhibition, pour point depression, etc. Petroleum-based lubricants are attributed to low biodegradability and toxicity. Demand for lubricants based on edible and nonedible plant oils or other renewable resources that are good for the environment is rising because of their enhanced lubricity, nontoxicity, and biodegradability. Biolubricants are synthesized by modifying plant oils chemically, by transesterification, estolide formation, epoxidation, etc. This chapter is intended to inform readers about renewable feedstocks for biolubricant production, comparison of physicochemical properties with petroleum-based lubricants, current scope, advantages, and challenges of biolubricant production in the future.

Keywords: Biolubricants, renewable, biodegradable, plant oils, chemical modification

Abbreviations

1.1 Introduction

Lubricants help solid bodies move closer to each other by lowering wear and friction surfaces that interacting [1]. These are majorly used in chain saws, engines, gear boxes, metal rolling mills, etc. Lubricating oils are necessary for a variety of other tasks in addition to their fundamental roles in reducing friction and wear, such as removing heat, preventing corrosion, transferring power, creating a seal for the liquid moving contacts, and suspending, as well as removing worn-out particles [2].

Among the most promising future markets, according to the Lead Market Initiative of the European Commission, is goods made from renewable raw materials. The utilization of renewable raw materials (RRM) by way of a feedstock can help conserve fossil fuels and lessen adverse environmental effects while producing utilities, chemicals, and different bioderived products. Additionally, it could benefit the agriculture, as well as forestry industries and spur developments for manufacturing products, like biolubricants and bioplastics [3].

Vegetable oils have great lubricating performance, are biodegradable, and can be recycled, making them a promising source of ecologically beneficial (green) lubricants [4].

Triglycerides, or tri-esters, have three long-chain fatty acids connected at the –OH groups through ester bond to the glycerol backbone and make up the majority of vegetable oils. These oils contain a tiny percentage of esters with one ester group from long-chain fatty acids and fatty alcohols with various chemistries [5]. Triglycerol esters from vegetable oil contain fatty acids with variable amounts of unsaturation, all of which have a comparable length (14–22 carbons) [6]. A large proportion of vegetable oils consist of various polar and nonpolar groups in the same molecule. These oils have polar groups and are hence amphiphilic, which enables vegetable oil to be incorporated as a boundary and hydrokinetic lubricant [7]. Almost 8% (12.4 million tonnes) of world’s manufacturing of renewable raw materials comes from Europe (EU-27), primarily from rape, sunflower, and soya.

The utilization of plant-based oils in lubricants depends on their fatty acid composition. Mainly, long-chain fatty acid-based plant oils are preferred for use in biolubricant manufacture. Palm, soya bean, rapeseed, and sunflower oils are hence majorly used [8]. The second largest category of products made from plant oils is lubricants. Lubricants are intricately manufactured goods of about 90% base oils along with useful additives to change inherent qualities. Vegetable oils are typically utilized for the purpose of base oils in biolubricants; however, only 50% of the oil needs to come from renewable sources to qualify as a biolubricant [9].

Biobased lubricants are used as hydraulic fluids, metal working fluids, grease, concrete mold release agents and chainsaw oils. These are majorly applied in mechanical parts, which is being utilized in ecologically sensitive regions like agriculture and machinery for forestry, jet-skis, snow mobiles, etc. Although it is currently a small portion of the overall lubricant market, the biolubricant sector is continually expanding. Similar to mineral oil alternatives, which are more accessible but still account for a relatively small fraction of the industry. Both bioderived as well as some synthetic lubricants contain biologic components. By 2023, 1.06 million tonnes of bioderived lubricants are anticipated to be consumed [10]. The worldwide lubricant market can be broken down into lubricant-based mineral oil (87.72%, 32.63 million tonnes), synthetic lubricants (9.95%, 3.70 million tonnes), and lubricants based on renewable resources (2.33%, 870000 tonnes), as represented in Figure 1.1.

The industrial reach of green lubricants is anticipated to rise to 15% and perhaps 30% in some regions over the next 15 to 20 years. This market is anticipated to increase significantly because of growing utilization of biobased lubricants in the manufacturing and transportation sectors [11].

The potential future shortage of oil and gas resources (whether in terms of availability or quantity) is a serious issue for everyone in the world. Ruling bodies all across the world are attempting to lessen their reliance on foreign sources of energy as a result. In addition, bioderived lubricants have become more popular as alternatives for traditional lubricants based on petroleum sources in a variety of applications, particularly the automobile sector. Despite their advantages, biobased lubricants are still a long way from being a reliable replacement. Biobased lubricants have low cold flow characteristics, poor thermooxidation, and low hydrolytic stability because they are often made from unrefined vegetable oils. However, these flaws could be fixed by chemically altering the oils derived from natural resources or adding additives to the oils [12].

Figure 1.1 Distribution of global lubricant market.

Vegetable oils have been utilized for lubrication needs for a long time. The unearthing of petroleum as well as the availability of inexpensive oils, however, led to the abandonment of this notion. Crude oils derived from fossil fuels are still utilized as primary raw material in the processing of fuels and lubricants. However, because of increased apprehension about ecological effects of lubricants based on nonrenewable resources, there has been a renewed attention to the usage of lubricants made from vegetable oils. Numerous businesses have created and sold biobased lubricants [13].

Because they preserve the mechanical characteristics of traditional lubricants, lubricants based on renewable resources are attractive substitutes for mineral oils. Bioderived lubricants have excellent lubricity, flash point viscosity index, and are biodegradable. They are made from edible and inedible vegetable oils [14].

The current chapter lays emphasis on how modern technological advancement can lead to improved manufacturing of bio lubricants. These technologies are primarily prospective for utilization of renewables as raw source, such as vegetable oils. However, there are certain constraints and impediments for full-scale implementation or commercialization like for example, the economics for development of biolubricants are not fully set or accustomed to manufacture and use of biolubricants as substitute to traditional lubricants based on petroleum sources; development of required technology and its standardization; testing and analysis in real time systems has not yet been performed on a commercial scale, etc. Nonetheless, the current research and findings in these domains can prove to be effective solution.

1.2 History

For hundreds of years, biobased materials have been utilized as efficient lubricants. Even though there has been evidence to show the usage of lubricating agents in the Copper Age, animal as well as vegetable oils had been...