Purification of H<inf>2</inf>-rich gas from methanol reformer by preferential oxidation over Pt-Ru/Al<inf>2</inf>O<inf>3</inf> catalyst

Abstract

A methanol reformer with a purification system was designed and investigated in this study. Hydrogen was produced by ATR (auto-thermal reforming), and reformate gas was purified by WGS (water gas shifting reaction) and PrOX (preferential oxidation). The investigated parameters were GHSV (gas hourly space velocity) and O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /CO (oxygen/carbon monoxide molar ratio). Experimental results showed that hydrogen concentration was 28.52% and carbon monoxide concentration was 7.67% in hydrogen-rich gas from ATR reformer. Through the water gas shifting reactor, CO concentration was as low as 0.81%. The improvement of CO was 98.58% under the GHSV=7800 h <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /CO=1.44. The reformate gas sampled in the outlet of preferential oxidation reactor, CO concentration was measured as low as 12 ppm at GHSV=3900 h <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . The overall H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> flow rate of 23.24 L/min could be supplied for the requirement of a 1.5 kW fuel cell system. By performing a 4-hour stability test, the CO could be controlled around as low as 50 ppm, and H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> concentration could be maintained at approximately 32%-33%.