K. Suresh Kumar Reddy

Solid support ionic liquid (SSIL) adsorbents for mercury removal from natural gas

Mercury removal is an integral part of gas-processing and coal combustion plants due to its implication on health, environment and process equipment. Utilization of impregnated carbons and metal sulfide-based adsorbents for mercury removal are common, however with limitations in adsorption capacity and life time. Continued efforts to develop porous carbon sorbents with better mercury adsorption capacity and kinetics are evident from the open literature with the recent focus being on solid support ionic liquid (SSIL)-based adsorbents with ionic liquid and chelating agents. However, reports on application of SSILs-based adsorbents for gas-phase mercury removal are not available in the open literature. Toward this objective, the present work attempts to synthesize three different SSILs adsorbents identified as SSIL (porous carbonu2009+u2009IL), SSILM (porous carbonu2009+u2009ILu2009+u2009MPTS), SSILA (porous carbonu2009+u2009ILu2009+u2009APTS–MBT) utilizing ultrasound-induced wet impregnation method. The adsorbents were subjected to characterization utilizing BET, XRD, FT-IR and SEM and were tested for its mercury adsorption capacity. The SSIL sorbents were found to possess higher order of magnitude adsorption capacity as compared to high-surface-area porous carbons and metal sulfide-based porous carbons. The adsorption capacity of the SSILs increased orders of magnitude with increase in adsorption temperature from 30 to 50xa0°C attributed to the predominance of the chemisorption. Among the three SSIL adsorbents, SSILA was found to exhibit highest equilibrium adsorption capacity of 36.9xa0mg/g at 50xa0°C. ΔH°, ΔS° and ΔG° indicate that elemental mercury adsorption on SSILA is a spontaneous and endothermic process.

Porous carbon nitrification process optimization for enhanced benzene adsorption

ABSTRACT Benzene is one of the aromatic hydrocarbons co-absorbed with acid gases during amine scrubbing that contribute to deactivation of catalyst in the Claus process. The present work attempts to modify the porous carbon surface through nitrogen group functionalization utilizing melamine as the nitrogen source, adopting Design of Experiments (DOE) with concentration of melamine, duration of impregnation and temperature of impregnation being the process variables, while BET surface area was the response variable. The surface modified samples were subjected to benzene adsorption. The optimal nitrogen content that had minimal pore damage was found to be less than 4.3%, with concentration of melamine being the most significant variable. Surface nitrogen functionalization reduced the surface area whereas the benzene adsorption capacity increased. Benzene adsorption capacity as high as 14.72 mmol/g was recorded at 45°C at a pressure of 235 mbar. Such high adsorption capacities have not been reported in open literature and the nitrogen functionalization augmented the adsorption to the tune of 20 to 30% at a pressure of 100 mbar, and only up to 10 to 15% at higher pressures. The adsorption isotherms as well as the kinetics of adsorption were modelled using the well-known popular models. Further, successful regeneration of the surface modified adsorbents were ensured through adsorption/desorption cycle experiments.

Enhanced separation of Toluene and Xylene through surface modified porous carbon matrix

ABSTRACT Aromatics that are present in the feed of the Claus sulfur recovery process are well known to poison the catalyst and hence continued efforts are being made within the scientific community to remove them. In this context, the present work attempts to develop superior adsorbents in comparison with contemporary adsorbents for removal of toluene and m-xylene. In a bid to improve adsorption properties, nitrogen-containing surface functional groups were successfully introduced onto porous carbon by minimizing pore damage while maximizing nitrogen content. The surface modified adsorbents were subjected to gas phase adsorption of toluene and m-xylene at 45°C to generate the adsorption isotherms. Toluene adsorption capacity for the modified adsorbent was observed to have increased by approximately 30% at pressure of about 20 mbar and m-xylene by about 10% at about 22 mbar. Several orders of magnitude increase in adsorption capacity was observed for both aromatics at pressures less than 10 mbar. Such high adsorption capacity have not been reported in literature and could potentially favorably alter the economics of aromatics removal in gas processing. Regenerability of nitrogen doped adsorbent was ensured through cyclic adsorption/desorption tests. The adsorption isotherms as well as the kinetics of adsorption were modelled.