Proceedings of International Conference on Advances in the Field of Health, Safety, Fire, Environment & Allied Sciences (HSFEA 2020). 1 Selective Catalyst Reduction (SCR) using Zeolite for Reduction of NOx Emissions in C.I. Engines Hemraj Chaudhary, Ayush Dwivedi, Venkateswarlu Chintala and Ashish Karn * Department of Mechanical Engineering, School of Engineering, University of Petroleum and Energy Studies, PO – Bidholi, Dehradun, 284007 India. * Email: akarn@ddn.upes.ac.in ABSTRACT The current study is aimed at the reduction of NOx emission (oxides of nitrogen) from a direct injection CI engine by SCR (selective catalytic reduction) technology. The SCR system was developed originally at the (CAER) Centre for alternate and renewable energy in which zeolite was used as a catalyst. The developed SCR system was integrated with a single chamber direct injection CI engine of 3.7 kW rated power at 1500 rpm. Experimental test results revealed the significant reduction of NOx emission with the SCR system at all engine loads. Experimental design of the investigation typified obtaining standard behavior of the engine i.e., without SCR followed by engine's information after the presentation of the SCR framework. It is investigated from the results exploratory tests results that hydrocarbon (HC) emission was highest about 20ppm at 10kg load yet at 4kg load it decreased to 16ppm. Carbon monoxide (CO) emission was moderately increased with the SCR system. NOx emission is minimum with SCR at all engine loading conditions as compared to without the SCR system. An experimental time study is also done & readings being taken in the time interval of 5 minutes. A difference of 10ppm hydrocarbon emission has been measured in between 15-20 minutes. In the NOx emissions, a difference of 97 ppm has been observed while using the SCR system. Henceforth, the introduction of SCR to the engine minimizes the emissions & enhances the combustion performance along with the benefit of reduction in NOx emissions. After the complete analysis of the data, the outcomes demonstrate a positive impact on the selective catalyst reduction (SCR) system set up with the engine. Keywords: Carbon monoxide emission, Direct-injection Compression Ignition Engine, hydrocarbons, oxides of nitrogen, Selective Catalytic Reduction. INTRODUCTION The Diesel-powered (CI) engine is a generally acknowledged main player owing to its load-bearing abilities and high fuel transformation efficiency. However, the high levels of (NOx) and PM (particulate matter) emissions emits due to the utilization of diesel in the CI engine [1]. The SCR technology has been widely used with diesel-powered compression ignition engines to maintain the emission level. In the present work, an