ADSORPTION OF CHLORINATED GASES IN H2 USING MODIFIED ZEOLITE NaY AND ACTIVATED CARBON

Abstract

Contamination of hydrogen chloride (HCl) and chlorinated hydrocarbon compound (VCM) in H2 feedstock causes adverse effects to the downstream petrochemical processes, even though in extremely low concentration. It is quite important to develop adsorbents which are able to uptake both chemicals. In this study, granular activated carbon (GAC) was modified by adding sodium with different concentrations, and zeolite NaY, using rice husk as a silica source, was synthesized and modified under different ratio of Si/Al (5 to 0.9). In addition, RH-SiO2, RH-MCM-41, Al2O3 balls were also studied. All adsorbents have been tested for their adsorption efficiency on both HCl and VCM in a continuous fixed bed flow column. The tests were carried out with initial concentrations of HCl and VCM at 600 and 20 ppm, respectively. Under the flow rate of 50 mL/min and bed of 6 g, for HCl adsorption, M-NaY-RH-1.87 showed the highest adsorption efficiency (1.444 gHCl/gadsorbent) followed by 6N-GAC, Al2O3 balls, GAC, RH-MCM-41, and RH-SiO2 respectively. For VCM adsorption, GAC provided the highest adsorption efficiency (0.0063 gVCM/gadsorbent) followed by 6N-GAC, RH-SiO2, and Al2O3 balls, respectively, while RH-MCM-41 and M-NaY-RH-1.87 were unable to capture VCM. For the mixed gases HCl and VCM, the mixture of GAC, 6N-GAC and M-NaY-RH-1.87 was found optimum with the ratio of 1/1/1 by weight, compared to a commercial one. Spent adsorbent contained some certain amount of sodium could be used for alternative fuel and alternative mixture in the cement kilns, for GAC and M-NaY, respectively. Co-processing in cement kilns will burns up the spent adsorbents.