Advances and Outlook on Desulfurization and Utilization of Tire Pyrolysis Oil: A Review
Xiaotong Liu, Zexuan Li, X.D. Lai Q.Q. Gou
Abstract
Globally, 150 million waste tires are generated annually. Various technologies have been proposed to utilize waste tires, including recycling, reuse, and incineration for heat recovery. However, the associated negative environmental impacts have hindered the industrial application of these methods. Tire pyrolysis, which transforms waste tires into fuel, offers an effective approach for utilizing discarded tires. Nevertheless, the tire pyrolysis oil (TPO) produced by this process is often of low quality and contains a high sulfur content, which restricts its direct use. Current hydrodesulfurization techniques, which are widely employed to eliminate sulfur compounds from TPO, are expensive and intricate. Although emerging oxidative desulfurization technology presents advantages in dealing with sulfur compounds that are difficult to remove via hydrodesulfurization, it also faces challenges such as oxidant cost and catalyst selection. TPO has chemical properties similar to diesel, and energy utilization efficiency can be substantially improved by optimizing the blending ratio, effectively reducing fuel costs. However, the high unsaturated hydrocarbon content in TPO affects its storage stability, necessitating the use of further refining processes. The light fractions of TPO, due to their high-octane number, are suitable for use as gasoline, but the issues of high nitrogen and sulfur content, which lead to combustion pollution, need to be addressed. Research also indicates that optimizing pyrolysis and distillation conditions can enhance the recovery rates of high-value compounds like limonene, thereby improving the economic efficiency of tire recycling. This paper reviews the desulfurization methods of pyrolysis oil and its resource utilization status, discussing the prospects of TPO as a fuel. Strategies for optimizing the desulfurization of pyrolysis oil and its resource utilization are proposed to promote the widespread application of TPO in practice, facilitating the efficient use of waste tire resources and environmentally friendly development.