Analytical comparison of emissions before and after using a three-way catalyzer connected to an SI gas engine operating with methane, natural gas, biogas, and different syngas content

This work compares two studies in which the spark ignition gas engine test was used with typical biogases generated in the rice industry: Bio70 (Study 1), Bio65 (Study 2), Syngas1 and Syngas2 (in both studies). Methane (Study 1) and natural gas (Study 2) were also used. From these studies, three different ignition advance angles were chosen: 20°, 35°, and 55°, to compare and analyze the effects of these fuels and their mixtures inside the engine. The emissions were also evaluated using a three-way catalytic converter connected to the engine. Study 1 demonstrated lower CO and hydrocarbon (HC) emissions than Study 2 for all conditions and all fuels, whereas NO_x emissions varied according to the engine operating conditions (λ and ignition advance angle). Except in the case of the syngases, Study 1 demonstrated higher indicated efficiency, electrical efficiency, and electrical power than Study 2. After the use of the three-way catalytic converter, HC and CO emissions were strongly reduced for all fuels and in different operational conditions. On the other hand, because the efficiency of the catalytic converter decreases abruptly in mixtures rich in NO_x, this pollutant was not removed when λ > 1. The comparison of the two studies and the emissions after the use of a catalytic converter is important as it shows specific ways to improve the use and efficiency of the fuels to encourage the development of renewable energy both in industry and in the transport sector.