Analysis of the Results of Experimental Sorbent for Chloride Compounds Removal

Abstract

This research pursues an objective to explore the composition and physicochemical characteristics of the domestic adsorbent obtained through processing alumina waste from the local industry upon completion of testing in the course of purification of hydrogen-containing gas from chlorine-containing compounds. Also, changes in the quantitative ratio of the main chemisorption products of harmful impurities (NaCl, AlCl 3 , AlCl 3 .6H 2 O and AlxCly (OH) z .nH 2 O) depending on modifiers of various nature were determined. The NaCl content in the adsorbents used rose symbatically in the concentration of main centers due to surface aluminates and sodium carboaluminate in the initial samples. The amount of coke-like deposits with a high hydrogen content С n Н 1.75-1.8n satisfactorily correlated with the concentration of strong secondary acid sites arising from the formation of aluminum chlorides and hydroxychlorides. The accumulation of coke-like deposits with graphitic structure during the testing of adsorbents under industrial conditions for gas purification in the regeneration of catalyst reforming did not exceed 1.5% of the mass.

Complex Processing of Adsorbent Used in the Purification of Hydrogen-Containing Gas

“…However, treatment with water for more than 24 hours is accompanied by the formation of an excessive amount of a low-concentrated suspension that is not suitable for further processing. The concentration of residual chlorine identified after calcining the washed granules in the temperature range of 670-570 K was below 0.5 %mass, and the specific surface area reached 280-300 m 2 /g due to the sublimation of aluminum chloride and burnout of carbon deposits [1] (Table 1). A feature of the morphology of the studied samples is the formation of a relatively loose layer with a thickness of about 250 µm and a denser middle part (Figure 2, photo on the right).…”

“…6H2O (broad lines with d = 6.0, 5.2, 3.89, 3.69, 3.29, 2.57, 2.3, and 2.05 Ǻ). An intense halo in the range of 2θ = 7.7-28° (Figure 1, diffractogram 1) indicates the presence of a mixture of several hydrolyzed forms of polynuclear hydroxo complexes of variable composition, which are expressed by the general formula [Al(OH)3-xCly]n,, where x varies within 0-3 [1].…”

“…The contact of the spent Axstrap-860 with water was accompanied by partial (15-20 %mass) destruction of granules up to a powdery statedue to their hygroscopicity. Therefore, the spent adsorbent was first washed with water, the whole granules were separated on a sieve, they were dried and calcined at 700-710 K to remove AlCl3 residues and coke-like deposits [1] (Table 1). Then the calcined granules were impregnated with an alkaline solution containing 195 g/L NaOH and 45 g/L KOH, taking into account the moisture absorption of 47-55 %mass, they were dried in air and put in a muffle furnace at a temperature not higher than 570 K. After settling the wash water suspension, a clear solution containing NaCl, chlorides and aluminum hydroxochlorides was separated by decantation.…”

“…The oil and gas processing industry along with the petrochemical and chemical industries, is a labor-intensive production and it is accompanied by the formation of various wastes that have a negative impact on the environment. In order to involve alumina waste from polyeth-ylene production for the industrial and economic circulation, the possibility of complex processing of this technogenic raw material into the followings is proved: 1) fresh adsorbent Uz-AD-1 for purifying hydrogen from chlorine-containing impurities at a naphtha reforming unit was proved [1]; 2) a component of carriers of catalysts for hydrotreating, prehydrotreating and demetallization of heavy oil feedstock [2]; 3) pseudoboehmite for the synthesis of an adsorbent of a protective layer for the process of oxidative conversion of hydrogen sulfide [3]. The adsorbent Uz-AD-1, which was developed by us, as well as its imported counterparts, is inevitably turned into a waste category after 1-2 years of operation.…”