Compact Catalytic Membrane Reactor for Efficient Conversion of Waste Plastics into Fungible Liquid Fuels

Only a small fraction of the 60 million tons of plastic used in the United States is recycled. Most plastics are not biodegradable. Due to wind and running water, more and more waste plastics naturally accumulate in waterways, oceans, and beaches. Since these collection or accumulation sites are distributed over a wide range of territory, it is not feasible to build large centralized processing plants to dispose it. An integrated compact catalytic reactor unit is proposed for distributed conversion of the plastic waste into fungible liquid fuels. In the reactor, the macro-molecules of plastic are cracked into smaller molecules on a solid catalyst, and the molecules within the range of gasoline and diesel fuels are taken out of the reactor through a catalytic membrane filter. Compared to conventional thermal processes, de-construction temperature of the plastic is substantially lowered so that the thermal energy consumption and environmental emissions are reduced. Direct production of the fungible liquid fuels simplifies the conversion process. It is projected that a commercial-scale reactor unit with 100 barrel per day (100 BPD) production capacity is compact enough to be prefabricated and transported by regular trucks and trailers. A laboratory bench-scale catalytic reactor and catalytic membrane filter will be built with 100g/h processing capacity and tested under realistic conditions to assess the impact of major risk factors on the practical viability of the technology and to demonstrate risk mitigation methods. Plastic products (bags, bottles, and containers, etc.) made of the five most common polymer materials, polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylenterephthalate (PET), and polycarbonates (PC) will be used as simulated feedstock with the addition of various impurities, such as soil, sand, and grease. An optimum cracking catalyst will be identified to convert those plastics into liquid fuels at reaction temperatures less than 500oC under nearly atmospheric pressure. The catalytic membrane filter will be demonstrated for complete removal of particulates and waxes from hot reactor effluent. With its compactness and minimal environmental footprint, the proposed reactor unit has potential for distributed plastic-to-fuel production at a small scale (tens to hundreds of BPD). This conversion technology may enable a new industry of substantial economy from the collection of plastic wastes, conversion, and fuel sales. If half of the plastic waste is converted to liquid fuels, the economic value is about $15 billion in the US and $65 billion/year worldwide.