Y zeolite equilibrium catalyst waste from fluidized catalytic cracking regenerated by electrokinetic treatment: An adsorbent for sulphur and nitrogen compounds

Abstract

The adsorption of sulphur, nitrogen, and aromatic compounds on a regenerated equilibrium catalyst (ecat-R) was studied using model and real diesel fuels. The ecat-R was obtained by electrokinetic treatment of an equilibrium catalyst (Y zeolites) waste from fluidized catalytic cracking (FCC) units. The studied model diesel fuel contained dibenzothiophene (1039 mg/L), quinoline (600 mg/L), and naphthalene (600 mg/L), as models for sulphur, nitrogen, and aromatic compounds, respectively, in n-decane as solvent. The ecat-R was characterized using X-ray diffraction, X-ray fluorescence, N 2 adsorption-desorption, thermogravimetric and differential thermal analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, and granulometry. The adsorption experiments were performed at 40 8C and 150 rpm. The results of the isotherm and kinetics studies were favourable; the material showed a high adsorption capacity for dibenzothiophene (2.8 mg S/g) and quinoline (6.3 mg N/g). The isotherm for naphthalene was less favourable (2 mg NAP/g). The process rapidly reached equilibrium in approximately 2 h. For real diesel fuel, the adsorption removal was 26 % for sulphur and 36 % for nitrogen.

Regeneration study of ecat-R as adsorbent for denitrogenation and desulfurization of diesel fuels

“…The electrolytes applied by this technique are sulfuric acid solution and sodium citrate solution [3,4,9,11]. When ecat did not completely lost its catalytic activity the electrokinetic remediation is made with sodium citrate solution (ecat-R-SC).…”

“…The ecat regenerated by electrokinetic treatment using 1M sulphuric acid (ecat-R-SA), was successfully studied as an adsorbent for sulfur, nitrogen and aromatic compounds present in model and real diesel fuel [4].…”

“…The sulfur and nitrogen concentration was determined using a Trace SN Cube analyzer according to methodology ASTM D 4629 and ASTM D5453 [4].…”

“…One waste that deserves special attention is the equilibrium catalyst (ecat) from cracking fluidized catalytic cracking units (FCC units), which is waste Class I (hazardous waste) [3]. The ecat matrix is composed of a clay suspension, containing mainly kaolin, alumina, silica oxides, faujasite (Y zeolite) and different rare earth cations [4]. It is common to insert rare earth cations into ecat matrix to improve the acidity, cracking activity and thermal stability of the catalysts [5,6].…”

“…The principles of CE of reducing and reusing are employed because regeneration processes (calcining and electrokinetic remediation) are used to minimize the entry of raw material into the process as well as to reuse ecat-R-SC in the FCC process. The successfully studied of ecat-R-SA as an adsorbent for sulfur, nitrogen and aromatic compounds present in model and real diesel fuel [4] recycles the catalyst in a new process. The recycle is the third principle of CE.…”