(164e) Evaluation of an Electro-Mechanical Piston Reactor for Propane Chemistry

The electrical-driven piston reactor is a new idea that converts electrical energy into mechanical and chemical energy. This reactor has a simple and compact design that can be used to perform chemical reactions. It operates in a similar way to a regular engine by compressing and heating the reactant feed gas or gas-liquid mixture in the reactor cylinder within very short time pulses (milliseconds), creating high cylinder temperatures and pressures that can trigger different chemical reactions and preserve meta-stable desired products. This reactor is based on well-established manufacturing infrastructures since conventional engines exist in various compact sizes and operate at a wide range of speeds, providing flexibility in production capacity. Past research on the piston reactor has mainly focused on using it to partially oxidize natural gas and produce synthesis gas ¹. This reaction is similar to the combustion chemistry used to drive engines, with the only difference being that the exhaust is the desired product.

This work aims to investigate the potential of utilizing the piston reactor driven by electrical energy to carry out propane chemistry. Propane is explored as a feedstock in this work as it produces valuable products such as hydrogen and alkane/alkene products, which are important building blocks for various chemical industries. First, a mathematical piston reactor model is built to predict the performance of the piston reactor running using propane. An experimental setup is built to provide proof of concept for this reactor concept. For this purpose, a single-zone zero-dimensional time-dependent thermodynamic model is developed, incorporating the POLIMI detailed mechanism which includes 484 species and 17790 reactions. The simulation studies showed that high intake temperatures are required to trigger a propane reaction > 950 K. Hence, to initiate the propane reaction within reasonable intake temperatures, reaction triggers such as the addition of oxygen or utilizing a spark plug, are needed

Proof of concept experiments was carried out utilizing a 25-cc piston reactor with a compression ratio of 8:1. Partial oxidation of propane was explored as an initial route. A feed mixture containing air and propane/helium was fed at an equivalence ratio of 1.53, at 1300 RPM, and at atmospheric temperature and pressure. A spark plug was used as a trigger to ignite the fuel mixture within the piston reactor chamber. Analysis of the exhaust revealed that synthesis gas was produced (H₂ and CO) with small traces of ethylene and acetylene. Moreover, the exhaust gas temperature due to the exothermicity of propane partial oxidation increased to around 250 ^oC, indicating the excess heat and power were co-generated.

The developed model was further used to guide experimental work and explore other potential means to carry out the propane chemistry within the piston reactor to produce more value-added chemicals. These studies included investigating the potential of co-feeding CO₂, and H₂O with oxygen to operate the reactor within the autothermal region. Figure 1 showcases a case study of one of the simulation results where co-feeding CO₂ shifts the product distribution toward the production of methane, and value-added olefins (ethylene, propylene). The simulation data are used to select an optimal operating window and do prove of concept validation experimentally.