Remoção de compostos sulfurados e nitrogenados de diesel modelo por adsorção em zeólita USY

Abstract

Petroleum is composed by aliphatic, naphtenic and aromatic hydrocarbons. These hydrocarbons can present heteroatoms such as, N, S, O or metals. These compounds cause damages to industrial equipaments and processes, as corrosion in pipelines and catalytic poisoning. They also hamper the environment and the human being health due to the toxic emissions generated from fuel burning. The more stringent environmental laws and the processing of heavier petroleum greatly increased the operational costs of the removal of heteroatom through hydrotreatment. Thus, there is a search for alternative low-cost methods to fit fuels within the limits established by the legislations. Adsorption is one of them. This work will investigate the use of zeolites USY and LaUSY, modified by the dry impregnation method, as adsorbents for the removal of sulfur, nitrogen and aromatic compounds from a model diesel (quinoline, dibenzothiophene, 4,6-dimethyldibenzothiophene, methylnaphthalene and n-hexadecane). Moreover, the use of toluene as regeneration solvent were evaluated. Single component (Langmuir, Freundlich, Langmuir-Freundlich and Redlich-Peterson) and multicomponent isotherms models (Non-Modified Langmuir, Competitive Langmuir, Uncompetitive Langmuir, Partial Competitive Langmuir and Sites Langmuir) were used to describe equilibrium data. The adsorbents were characterized by XRD, XRF, N2 adsorption, FTIR and NH3-TPD techiniques. The adsorption capacity of both solids increases in the following order: aromatic hydrocarbon < organosulfur << organonitrogen. The LaUSY is more selective for the removal of sulfur coumpounds in the presence aromatic hydrocarbon. All single component isotherm models described with high accuracy the removal of nitrogen and sulfur compounds. For binary solutions, “Langmuir-Sites” isotherm model was the one that better represented the competitive isotherm in the presence of n-C16 or toluene.