Transesterification of commercial waste cooking oil into biodiesel over innovative alkali trapped zeolite nanocomposite as green and environmental catalysts

Advancements in Basic Zeolites for Biodiesel Production via Transesterification

The excessive utilization of petroleum diesel has led to the depletion of fossil resources and severe environmental pollution. Biodiesel produced from renewable triglycerides (TGs) or waste lipids is a low-emission fuel substitute for diesel. Biodiesel is mainly produced by transesterification reactions over homogeneous base catalysts with excellent activity and low cost. In comparison, solid base catalysts are more attractive due to their lower environmental impact and simpler production and purification processes. It remains a challenge to further improve the stability and activity of solid base catalysts. Because of the high surface area, superior stability, and tunable basicity, basic zeolites, especially two-dimensional zeolites, have emerged as promising solid basic catalysts for the transesterification of TGs. In this review, we present recent advancements in the synthesis, characterization, and catalytic performance of basic zeolites for the transesterification of TGs. Challenges and development prospects of basic zeolites for biodiesel production via transesterification are also pointed out. We expect that this review will inspire the more efficient and rational design of zeolites for sustainable fuel production.

Synthesis of K+ and Na+ Synthetic Sodalite Phases by Low-Temperature Alkali Fusion of Kaolinite for Effective Remediation of Phosphate Ions: The Impact of the Alkali Ions and Realistic Studies

Two sodalite phases (potassium sodalite (K.SD) and sodium sodalite (Na.SD)) were prepared using alkali fusion of kaolinite followed by a hydrothermal treatment step for 4 h at 90 °C. The synthetic phases were characterized as potential adsorbents for PO43− from the aqueous solutions and real water from the Rákos stream (0.52 mg/L) taking into consideration the impact of the structural alkali ions (K+ and Na+). The synthetic Na.SD phase exhibited enhanced surface area (232.4 m2/g) and ion-exchange capacity (126.4 meq/100 g) as compared to the K.SD phase. Moreover, the Na.SD phase exhibited higher PO43− sequestration capacity (Qmax = 261.6 mg g−1 and Qsat = 175.3 mg g−1) than K.SD phase (Qmax = 201.9 mg g−1 and Qsat = 127.4 mg g−1). The PO43− sequestration processes of both Na.SD and K.SD are spontaneous, homogenous, and exothermic reactions that follow the Langmuir isotherm and pseudo-first-order kinetics. Estimation of the occupied active site density validates the enrichment of the Na.SD phase with high quantities of active sites (Nm = 86.1 mg g−1) as compared to K.SD particles (Nm = 44.4 mg g−1). Moreover, the sequestration and Gaussian energies validate the cooperation of physisorption and weak chemisorption processes including zeolitic ion exchange reactions. Both Na.SD and K.SD exhibit significant selectivity for PO43− in the coexisting of other common anions (Cl−, SO42−, HCO3−, and NO3−) and strong stability properties. Their realistic application results in the complete adsorption of PO43- from Rákos stream water after 20 min (Na. SD) and 60 min (K.SD).

Synthesis and Characterization of rGO@ZnO Nanocomposites for Esterification of Acetic Acid

In the present work, the aim is to synthesize reduced graphene oxide (rGO) and zinc:reduced graphene oxide composite catalysts (ZnO:rGO) for esterification of acetic acid with n-heptanol. The physical and chemical characteristics of the rGO and rGO-metal oxide composite catalysts such as textural surface characteristics, surface morphology, thermal stability, functional groups, and elemental analysis were studied. The surface areas of rGO, ZnO_(0.5 M), and ZnO_(1 M) were recorded, respectively, at 31.72, 27.65, and 36.19 m² g^-1. Furthermore, esterification reaction parameters such as the reaction time, catalyst dosage, and reaction temperature for acetic acid were optimized to check the feasibility of rGO-metal oxide composites for a better conversion percentage of acetic acid. The optimized catalyst was selected for further optimization, and the optimum reaction parameters found were 0.1 wt % of catalyst, 160 min reaction duration, and 100 °C reaction temperature with a maximal yield of 100%. At 110 °C, the reaction conducted in the presence of 0.1 g of catalyst displayed more yield than the uncatalyzed reaction.

The Catalysed Transformation of Vegetable Oils or Animal Fats to Biofuels and Bio-Lubricants: A Review

This review paper summarizes the current state-of-the-art of the chemical transformation of oils/fats (i.e., triacylglycerols) to the use of biofuels or bio-lubricants in the means of transport, which is a novelty. The chemical transformation is necessary to obtain products that are more usable with properties corresponding to fuels synthesized from crude oil. Two types of fuels are described—biodiesel (the mixture of methyl esters produced by transesterification) and green diesel (paraffins produced by hydrogenation of oils). Moreover, three bio-lubricant synthesis methods are described. The transformation, which is usually catalysed, depends on: (i) the type and composition of the raw material, including alcohols for biodiesel production and hydrogen for green diesel; (ii) the type of the catalyst in the case of catalysed reactions; (iii) the reaction conditions; and (iv) types of final products. The most important catalysts, especially heterogeneous and including reaction conditions, for each product are described. The properties of biodiesel and green diesel and a comparison with diesel from crude oil are also discussed.

Sustainable environmental management and related biofuel technologies

Environmental sustainability criteria and rising energy demands, exhaustion of conventional resources of energy followed by environmental degradation due to abrupt climate changes have shifted the attention of scientists to seek renewable sources of green and clean energy for sustainable development. Bioenergy is an excellent alternative since it can be applied for several energy-requirements after utilizing suitable conversion methodology. This review elucidates all aspects of biofuels (bioethanol, biodiesel, and butanol) and their sustainability criteria. The principal focus is on the latest developments in biofuel production chiefly stressing on the role of nanotechnology. A plethora of investigations regarding the emerging techniques for process improvement like integration methods, less energy-intensive distillation techniques, and bioengineering of microorganisms are discussed. This can assist in making biofuel-production in a real-world market more economically and environmentally viable.