Development of heterogenous Bronsted acid catalyst from rubber tire waste for biochemical production from biomass

A rubber tire is a thermoset polymer that is flexible and connected by 3D framework from vulcanization. The growth of vehicle industries increases the demand for rubber tires, resulting in high rubber tire waste affecting the environment. Utilization of rubber tire waste is one of the methods to reduce environmental concerns as follows as Bio-Circular-Green-Economy (BCG). For example, recycling rubber tire waste for new products, use of rubber tire waste as a heating source, and pyrolysis of rubber tire waste for fuels. Although these methods seem promising, the use of rubber tire waste to new products leads to a drop in physical properties and burning rubber tire waste to generate heat causes air pollution.

            From the concerns above, many researchers have developed a way to utilize rubber tires in a new applications such as catalysts and adsorbents. To synthesize a rubber tire as a solid acid catalyst, the rubber tire is pyrolyzed at a high temperature to convert rubber tires to carbon. Then, the resulting carbon will be developed further into catalysts or adsorbents. Although this method seems promising, the process is complex and involves pyrolysis, leading to high energy consumption.

            This research aims to develop a solid acid catalyst from rubber tire waste using an uncomplex method and low energy consumption by the sulfonation reaction of rubber tires. The effects of catalyst synthesis were studied on the efficiency and stability through the esterification of levulinic acid and methanol as a probe reaction against a commercial solid acid catalyst (Amberlyst-15). The sulfonated tire waste, synthesized under 150°C and 98% H₂SO₄ concentration showed higher catalyst performance than Amberlyst-15 up to 10% conversion with high product selectivity at 98% conversion and catalyst recyclability [1-3]. This research approach addresses the environmental impact of waste tires and contributes to sustainable catalyst development, paving the way for an eco-friendly waste management strategy.