ASIAN JOURNAL OF CHEMISTRY ASIAN JOURNAL OF CHEMISTRY https://doi.org/10.14233/ajchem.2018.21210 INTRODUCTION Exhaust gases from internal combustion engines of vehicles and industrial combustion process contain noxious oxides of nitrogen (NOx), which is well-known for its detrimental contri- bution to our environment [1,2]. As a consequences of environ- mental hazards, strict restrictions have been imposed time to time to control its emission from both stationary and mobile sources [3-6]. Catalytic abatement of (NOx) attracted lots of attention as direct decomposition of this pollutant is kinetically not suitable due to its high activation energy barrier [7]. There- fore, catalytic reduction of NOx is one of the feasible options to reduce this pollutant into innocuous gas. Three-way catalyst (TWC) was introduced in automobiles in the late 1970s to control CO, NOx and hydrocarbon together and was successful until introducing lean-burn technology, which improves fuel economy [8,9]. In lean-burn mode of operation auto-vehicles has to run both in oxidizing as well as reducing environment and three-way catalyst got deteriorates particularly for controlling NOx [10,11]. Also demand for precious metals, which are essential ingre- dients of three-way catalyst rises and lessening of their amount is very essential to save these precious metals [12]. There are two Catalytic Activity of 0.4 % Rhodium Supported Microporous AlPO 4 -5 Catalyst for NO-CO-C 3 H 6 -O 2 Reactions AHMED JALAL SAMED 1,* and MASATO MACHIDA 2 1 Department of Chemistry, School of Physical Sciences, Shahjalal University of Science & Technology, Sylhet-3114, Bangladesh 2 Department of Nano Science and Technology, Graduate School of Science and Technology, Kumamoto University, 2-39-1, Kurokami, Kumamoto, 860-8555 Japan *Corresponding author: E-mail: ajf-che@sust.edu Received: 2 January 2018; Accepted: 28 February 2018; Published online: 30 April 2018; AJC-18879 Temperature-programmed reactions of mixtures of NO, CO, C3H6 and O2 were investigated over rhodium supported on microporous AlPO4-5 catalyst. Same reactions were studied after treating the catalyst in a stream of H2 to evaluate the catalytic performance after reduction treatment. Microporous AlPO4-5 was synthesized hydrothermally using triethylamine as structure directing agent and then been used as a support for rhodium metal. A lower amount of rhodium (0.4 wt %) supported on microporous AlPO4-5 catalyst exhibited satisfactory light-off at temperature (T50 % = 300 ºC) with a steep rise in conversion efficiency after aging the catalyst at 900 ºC for 25 h in a stream of 10 % H2O/air. Outstanding result was observed after reduction treatment of the catalyst, where light-off shifted to a lower temperature 200 ºC maintaining steep rise in conversion efficiency. Rhodium nanoparticles were well dispersed on the high surface area microporous AlPO4-5 material, which is believed to be the key factor for exhibiting excellent catalytic activity both in the oxidizing as well as reducing environment. This newly developed rhodium supported microporous AlPO4-5 catalyst with minimum rhodium loading having excellent catalytic performance after reduction treatment, has the potential to serve as a new generation there-way catalyst. Keywords: Microporous, AlPO4-5, Rhodium nanoparticle, Three-way catalyst, Reduction treatment. Asian Journal of Chemistry; Vol. 30, No. 6 (2018), 1273-1276 options to solve this problem. One is the alternative to precious metal and another one is development of support material for the precious metal. Much efforts have been directed by the resea- rchers in the first option but little success has been achieved. Because there is no viable substitute of precious metals for exhi- biting unparallel activity to control noxious automotive pollutants. To address this issue, we focused on the second option and devel- oped varieties of new support materials for Pt and Rh metal for dissipating NOx by using these supported catalysts [13-16]. For NOx abatement, previously we reported Rh supported dense AlPO4 catalyst for the catalytic removal of NOx [17]. We got promising catalytic activity along with thermal stability using this support having low surface area. Then we started our new journey with a view to synthesize new phosphate materials [13]. In the context of development of support material by lesse- ning precious metals, we got promising result by using high surface area mesoporus support for Pt catalyst [16]. Keeping this into our mind we started searching new type of porous phos- phate materials for the Rh metal. Among the porous phosphate materials with pore sizes near molecular dimensions such as aluminophosphate (AlPO), has physical/chemical properties similar to zeolites and more important applications have been