In the last few years, there is a general shift observable toward greener lubrication, fueled amongst others by policy initiatives such as the European Green Deal in consistency with the UN Sustainable Development Goals. At least 70 vol% of a lubricant is composed of a specific base oil, the rest is a variation of additives altering the lubricant properties (enhancing or suppressing existent base oil properties or adding new properties) to be operational for a particular field of application. So, in terms of sustainability, biodegradability, bioaccumulation, and toxicity the type of base oil plays a major role, which makes environmentally harmful petroleum-based lubricant formulations highly problematic for future applications. Hence, this leads to an ever-growing demand of environmentally friendly lubricant alternatives. Within the scope of this review lies the investigation of bio-based, bio-derived, and other sustainable lubricant components that could serve as promising replacements for conventional petroleum-based formulations, in accordance with the principles of green chemistry and tribology. As recycling is embraced by the term sustainability, waste-derived components of non-biological origin are also included in this work. An overview of studies on the tribological performance such as friction and wear properties of these sustainable and benign lubricant components is given. GRAPHICAL ABSTRACT

The growing demand for sustainable lubricant solutions is driving the exploration of bio-based materials that deliver comparable performance to conventional, primarily fossil-based lubricant chemistries. This study focuses on squalane as a sustainable base oil, which can be derived from different renewable sources. A total of two squalane products were evaluated for thermal-oxidative stability and benchmarked against a polyalphaolefin, PAO 4, of the same total carbon number. Oils artificially altered in a closed reactor were sampled and subjected to conventional lubricant analyses, including infrared spectroscopy, to determine the changes due to autoxidation over time. For in-depth information, direct-infusion high-resolution mass spectrometry and gas chromatography coupled with triple quadrupole mass spectrometry were employed to identify degradation products from thermo-oxidative stress. The results revealed substantial variability in the stability of squalane products, suggesting that differences in raw materials and production processes have a major impact on their performance, including rheological properties. The degradation products of polyalphaolefin and squalane, identified through detailed mass spectrometry, were analyzed to understand their impact on conventional physicochemical properties. While polyalphaolefin predominantly generated carboxylic acids with short to medium chain lengths as degradation products, squalane oxidation produced carboxylic acids with medium to long chain lengths as well as several alcohols and ketones. Despite these differences, squalane demonstrates its potential as a non-fossil hydrocarbon base oil, as squalane products matched and even exceeded PAO 4 stability.

Common B7 biodiesels consist of mixtures of mineral oil-based diesel and 7% fatty acid methyl ester (FAME). While biocontent increase can be achieved with these blends at high-quality levels during cold temperature periods, fuel filter blocking events are reported from time to time. Based on a preliminary study on fuel filters, the selection of compounds responsible for filter blocking could be narrowed down to saturated monoglycerides (SMGs). The most abundant SMGs in Europe are 1- and 2-monopalmitin (1-C16:0, 2-C16:0) and 1-monostearin (C18:0), based on the FAME origin. Until now, there has been no simple, precise, and accurate method to quantitatively detect those SMGs in the B7 matrix, which was the aim of the following work. An improved gas chromatography electron ionization tandem mass spectrometry method was developed for the quantitative detection of 1-C16:0, 2-C16:0, C18:0, and C20:0 SMGs. During the method improvement, (a) the sample preparation and (b) the calibration were optimized for low concentrations. (c) The samples were analyzed by multiple reaction monitoring focusing on specific qualifier and quantifier ions with optimized collision energies, (d) time segments and improved scan time were implemented, and (e) limits of detection and limits of quantification were determined. The time-stability of SMG standards in CHCl3 with 4% neat biodiesel and the discrimination effects of the standard components were evaluated to assess method reliability. Overall, a highly sensitive and precise method for the improved detection of SMGs in biodiesel is presented.

The challenge of moving to a carbon‐free energy economy is highlighted in the context of technology and materials restrictions. Many technologies needed for the so‐called energy transition depend on critical metals such as platinum, lithium, iridium and cobalt. Here we focus on solid borohydride salts as hydrogen carriers, studying catalysts for hydrogen release. We combine metal 3D printing technology and a Raney‐type leaching process to make structured macroscopic catalyst/reactor monoliths of cobalt, aluminium and stainless steel with well‐defined micropores. Remarkably, the blank catalyst samples, which are made only from aluminium and stainless steel (Al‐SS), show high activity and, importantly, high stability in borohydride hydrolysis, with no mass loss and no surface poisoning. The batch results are confirmed in a continuous setup running for 96 h. Catalyst performance is attributed to the stable porous structure, the mechanical stability of the stainless steel macrostructure, and the presence of accessible Al(OH)x sites. This research shows a clear contribution to sustainability based on multi‐factor comparison: The Al‐SS catalyst outperforms the state‐of‐the‐art on mechanical and chemical durability, it is both PGM‐free and CRM‐free, and its preparation follows a simple, scalable and low‐waste procedure.

The growing demand for sustainable lubricant solutions is driving the exploration of biobased materials that can deliver comparable performance to conventional, primarily fossil-based lubricant chemistries. This study focuses on squalane as sustainable base oil, which can be derived from different renewable sources. A total of three squalane products were evaluated for ther-mal-oxidative stability and benchmarked against a polyalphaolefin PAO4 of the same total carbon number. Oil samples subjected to artificial alteration in a closed reactor underwent standard lub-ricant analyses, including infrared spectroscopy, to determine the conventional degradation changes over time. Additional in-depth information, by direct infusion high-resolution mass spec-trometry and gas chromatography coupled with triple quadrupole mass spectrometry were em-ployed to identify oxidation degradation products. The results revealed substantial variability in the stability of squalane products, suggesting that differences in raw materials and production processes have a profound influence on their performance, as well as rheological properties. Furthermore, detailed mass spectrometry analysis was applied to identify degradation products specific to poly-alphaolefin and squalane, respectively, and to understand their impact on the conventional phys-icochemical properties. While polyalphaolefin predominantly generated short-chain carboxylic acids as degradation products, squalane oxidation also produced several alcohols and ketones. Despite these differences, squalane demonstrates potential as a non-fossil hydrocarbon-based base oil, as squalane products matched and even outperformed stability of PAO4.

This investigation presents a one-pot electrochemical depolymerization of lignin, coupled with in-situ extraction, to enhance product recovery and process efficiency. Kraft lignin was dissolved in an aqueous sodium carbonate solution and covered with a methyl isobutyl ketone (MIBK) layer. The electrocatalytic reaction, conducted at −350 mA, facilitated lignin depolymerization, yielding a lignin-based bio-oil (LO) composed of a mixture of aromatic compounds, smaller aliphatic molecules such as alcohols, ketones, and acids, as well as sugar derivatives. Size exclusion chromatography confirmed a substantial reduction in molecular and dispersity, indicating effective and controlled lignin depolymerization. MIBK was chosen as an effective solvent for in-situ extraction due to its proven efficacy, reusability, and compliance with sustainable solvent guidelines. Preliminary tribological assessments demonstrated that, despite a higher coefficient of friction (COF) compared to conventional ester oils, LO provided comparable wear resistance, with minimal surface damage observed. Wear imaging further revealed stronger, more resilient surface interactions, suggesting LO’s potential as an eco-friendly lubricant with enhanced durability. These findings mark a critical advancement in lignin valorization, successfully overcoming challenges in product recovery from depolymerization processes and demonstrating its viability as a sustainable alternative to petroleum-based lubricants. Future studies will focus on optimizing formulation and fine-tuning performance to expand LO’s application potential in industrial lubrication