Bio-Derived Porous Graphitic Carbon as Highly Efficient Mercury Scavenger from Natural Gas Streams

Abstract

Abstract Remediation of toxic mercury emissions in the form of elemental mercury (Hg°) from the well head has become a dire necessity in the fast paced natural gas processing industries, as even low levels of mercury can damage the cryogenic aluminum heat exchangers and other plant equipment. Also, enforcing stringent measures to reduce the effect of elemental mercury is of great environmental concern owing to its high toxicity, volatility, chemical inertness and neurological health impact. Thus, synthesis of efficient and cost-effective porous carbon based sorbents having high selectivity and sorption capacity has attracted considerable interest, and is a widely used and industrially preferred technique. The present work focuses on the development of low cost and biomass derived graphitic carbon as a potential candidate for scavenging mercury from natural gas processing as well as refining operations. The bio-derived porous graphitic carbon (PGC) material was fabricated through a facile and sustainable method, from the natural biopolymer (calcium alginate) by pyrolyzing at 900°C under an inert atmosphere. The performance was examined by testing the graphitic carbon in a bench scale setup and using simulated environment mimicking the plant conditions. The adsorption results show evidence that accessible high pore volume, hierarchical pore structure, coupled with long range ordering enables the proposed PGC as an efficient low cost adsorbent for removing elemental mercury from natural gas. The high adsorption capacity of 626 μg/g exhibited by the graphitic carbon at an adsorption temperature of 50°C, outperformed the leading porous carbon currently used for gas phase mercury removal. Also, the increasing cost of conventional sorbents make these poly saccharide based biomaterials an attractive candidate. All these findings demonstrate the promising solutions offered by PGC for scavenging elemental mercury from natural gas.