Methane tri-reforming is an efficient route to produce syngas. Distributing one component through a micro-porous membrane, namely side-feeding procedure, is an effective method for controlling reactions pathway and achieving the higher performance in membrane reactors. More recently, Alipour-Dehkordi and Khademi (2019) suggested a feasible and beneficial membrane multi-tubular reactor with O-2, H2O or CO2 side-feeding policy to describe the methane tri-reforming for producing a suitable syngas for the methanol and dimethyl ether direct synthesis processes. To complete the previous research, a theoretical study was presented to detect the role of effective parameters, including molar flow rate of feed components, membrane thickness, shell-side pressure, and inlet gas temperature on the H-2/CO ratio, CH4 conversion, H-2 yield, and CO2 conversion. Several results were observed, however one of the most attractive results was to achieve CO2 conversion up to 40% in these configurations by controlling the influencing parameters (compared to CO2 conversion in the conventional tri-reformer (i.e., 11.5%)); that would be favorable for the environment. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.