(430g) Reciprocating Engine As a Chemical Reactor - Review of Design Types, Potential Reactions, Catalysts, and Technical Challenges

A wide variety of chemical reactions are endothermic, and thus require a high temperature or a combination of high temperature and high-pressure to occur. When multiple reactions are conducted at those conditions, the concentrations of the products ultimately formed are controlled by the times spent at the different conditions during the residence time in the reactor. In typical steady-state conventional chemical reactors, these conditions remain fixed. With a view to explore options for simple, safe and compact chemical reactors that preserve wanted metastable initial products from sequential unwanted reactions, academic and industrial researchers have tried to repurpose reciprocating piston equipment or an “engine-like” design to be used as a chemical reactor [1].

In such a reactor: gas, liquid or multiphase chemical reactions take place inside the cylinder volume which is compressed and expanded close to adiabatic by a reciprocating piston. Very high pressures of hundreds of bars and high temperatures even above 1500 K, can be realized for a short time typically in the millisecond's range. For some specific designs, sub-millisecond pulses with 3000 bar, and 4000 K have been claimed that are not feasible in conventional chemical reactors [2]. The integrated reactant compression, heating, expansion, and fast quenching cyclic steps open up a new unexplored window of operation with chemical reactions conducted in transient mode. Moreover, the fast quench in principle allows the reactor to preserve a target non-equilibrium state, at which the reaction has produced a product with an optimal yield and efficiency. Typically the reactor design can be compact and hence suited for modular operation. Industrial application could be realized by employing both, economy of scale and numbers. Next to homogeneous chemical conversions, this reactor design could also be used to synthesize nanoparticles [3]. Overall, the reciprocating piston chemical reactor offers several pronounced advantages over conventional reactors, next to the obvious technical challenges that have to be resolved. As yet this technology has not been demonstrated at commercial scale. Technical challenges to be addressed include lack of kinetic and thermodynamic analysis, reactor and spatial control and stability, lubrication, fouling, leakages and safety analysis, scale-up strategy, process economy and demonstration at pilot and large scale.

This work will present a comprehensive chronological review of journals, patents and other published resources that detail the previous attempts of developing a reciprocating piston engine as a chemical reactor; The focus will be on the prize, i.e., major applications, and confronted technical challenges. An outline of the different types of reciprocating piston reactor designs and their operating window will be presented. A section will be dedicated to catalysis in such a reactor design including types and ways to implement it. Selected chemical reactions with significant industrial potential will be reviewed. For example, reforming, cracking and other reactions [4-7]. Finally, an outlook for the potentials and limitations of this reactor technology will be presented.

Acknowledgments

This work was made possible by funding from Qatar National Research Fund (QNRF) project number NPRP12S-0304-190222 and co-funding by Qatar Shell Research and Technology Center (QSRTC). The statements made herein are solely the responsibility of the author(s).

References.

[1] A. Kronberg, “Technology Report - Pulsed compression reactor,” Eur. ROADMAP Process Intensif., pp. 1–18, 2008.

[2] Roestenberg, T. The Application of a Pulsed Compression Reactor for the Generation of Syngas from Methane, PhD thesis, Universiteit Twente Universiteit, (2011).

[3] Suzuki S. and Mori S. Flame Synthesis of Carbon Nanotube through a Diesel Engine Using Normal Dodecane/Ethanol Mixing Fuel as a Feedstock. J. Chem. Eng. Japan, vol. 50, no. 3, pp. 178–185, 2017.

[4] Lim, Emmanuel G., Dames, Enoch E., Cedrone, Kevin D., Acocella, Angela J., Needham, Thomas R., Arce, Andrea, Cohn, Daniel R., Bromberg, Leslie, Cheng, Wai K., Green, William H. The engine reformer: Syngas production in an engine for compact gas-to-liquids synthesis. Can. J. Chem. Eng., vol. 94, no. 4, pp. 623–635, Apr. 2016.

[5] Karim, G. A., & Moore, N. P. W. (1990). The production of hydrogen by the partial oxidation of methane in a dual fuel engine (No. 901501). SAE Technical Paper.

[6] Hiratsuka, Y. (1963, January). Production of synthesis gas by an internal combustion engine. In 6th World Petroleum Congress. World Petroleum Congress.

[7] Anderson, D. M., Nasr, M. H., Yun, T. M., Kottke, P. A., & Fedorov, A. G. (2015). Sorption-Enhanced Variable-Volume Batch–Membrane Steam Methane Reforming at Low Temperature: Experimental Demonstration and Kinetic Modeling. Industrial & Engineering Chemistry Research, 54(34), 8422-8436.