State-of-the-art catalysts for clean fuel (methyl esters) production—a comprehensive review

Abstract

There has been growing and recent interest in using non-edible feedstocks such as waste animal fats as alternate to vegetable oils in biodiesel production to address food vs fuel debate. The waste animal fats are cost effective and yield the biodiesel of good quality. Therefore, waste animal fats are appealing and excellent feedstocks to produce biodiesel. Commercially, the biodiesel is obtained by transesterification reaction of triglycerides present in oil/fat with alcohol in presence of homogeneous base catalysts. However, free fatty acids found in low-quality oil feedstocks are particularly sensitive to homogeneous base catalysts, necessitating extra acid pretreatment and neutralization procedures that not only raise the overall expense of producing biodiesel but also create environmental contamination. Optimistically, the use of solid catalysts can offer an environmentally friendly, cost-effective, and practical route for the manufacture of biodiesel from inexpensive oil feedstocks, including waste animal fat. The present review article covers catalyzed transesterification/esterification using various catalysts with particular focus on use of heterogeneous catalysts when using waste animal fat as feedstock for biodiesel production. Particularly, the properties of biodiesel obtained from waste animal fats are also compared to biodiesel properties of standard organizations such as European Committee of Standardization and the American Society for Testing and Materials. Moreover, this paper also offers future research directions that can direct researchers to fill in knowledge gaps impeding the creation of efficient heterogeneous catalysts for long-term biodiesel generation. To the best of our knowledge, the valorization of waste animal fats from slaughterhouse is not feasible and have some techno-economic concerns. However, this technology is more desirable considering environmental point of view to address the pollution problems caused by these wastes.

A review on thermochemical based biorefinery catalyst development progress

“…[16][17][18] However, the selection of a suitable catalyst, which is cheap and can work for a long time, is the main challenge of this process. [19][20][21][22][23][24][25][26][27] In addition, gasication occurs at high temperature (>700 °C), which requires a high source of heat and also special materials for the reactor. These lead to the high cost of operation.…”

RSM modelling and optimization for performance evaluation of biodiesel production process from livistona jenkinsiana using NaOH as a catalyst

“…Based on titration analysis, the raw oil is found to have a high free fatty acid (FFA) content of 9%. This level of FFA is considered to be very high for using sodium hydroxide (NaOH) as a catalyst [36]. With a high FFA content, there is an increased likelihood of saponification reactions occurring instead of transesterification reactions [37].…”

A Review on Biodiesel Production, Analysis, and Emission Characteristics from Non‐Edible Feedstocks

“…Currently, biodiesel production is achieved by using diverse edible and non-edible oils. [16] However, the consumption of edible oils to produce biodiesel results in food vs fuel debate. On the other hand, the non-edible (e. g., Jatropha, karanja, polanga, royna, and neem etc.)…”

“…Biodiesel is a famous and well‐known liquid biofuel which is derived from the different kinds of oils extracted from the biomasses. Currently, biodiesel production is achieved by using diverse edible and non‐edible oils [16] . However, the consumption of edible oils to produce biodiesel results in food vs fuel debate.…”