Nitrogen compounds removal from oil-derived middle distillates by MIL-101(Cr) and its impact on ULSD production by hydrotreating

Abstract

Oil-derived middle distillates (straight-run gas oil and mixture with light cycle oil and coker gas oil) for Ultra-Low Sulfur Diesel (ULSD) production by HyDroTreating (HDT) were pretreated by selective Nitrogen Organic Compounds (NOC) adsorption. Highly crystalline Metal-Organic Framework (MOF) MIL-101(Cr) prepared with propylene oxide (proton scavenger) as textural improver was used to that end. MOF was characterized by N2 physisorption, X-ray diffraction, thermal analysis, infrared, Raman and UV-vis spectroscopies, and electron microscopy (SEM and HR-TEM). NOC removal was carried out at room temperature and atmospheric pressure, the adsorbent being easily regenerable under mild conditions. Extruded MOF efficiently removed NOC from real feedstocks to concentrations ~ 80 ppm which allowed ULSD production at much milder conditions to those used during pristine feedstocks HDT. Operating temperature could be significantly diminished (from 350 to 330 °C, at 56 kg cm−2 (5.77 MPa), LHSV = 1.5 h−1, H2/oil = 2500 ft3 bbl−1 (445 m3 m−3)) which could notably prolong cycle life of NiMo/Al2O3 formulation used.

Adsorptive Denitrogenation of Coker Diesel over Carbon-Based Adsorbents for Producing Ultralow-Sulfur Diesel

“…Many studies have been conducted to improve the ultradeep HDS performance of the middle distillates. ,− It has been found that the coexisting organic nitrogen compounds, such as aniline, pyridine, quinoline, acridine, indole, carbazole, and their derivatives, in the liquid hydrocarbon streams, even at very low concentrations, strongly poison the hydrotreating catalysts by competitive adsorption on the active sites of the catalyst, and thus significantly inhibit the deep HDS of the middle distillates for producing ULSD. − It has been reported in the literature that the removal of these nitrogen compounds from feedstock prior to deep HDS could remarkably improve the deep HDS performance. − Furthermore, the nitrogen compounds in fuels cause odor and color and reduce the thermal and oxidative stability of fuels . Consequently, deep denitrogenation of liquid hydrocarbon streams for producing ultraclean fuels is becoming an increasingly important research subject worldwide.…”

“…Many approaches have been employed in recent years by using nonhydrotreating processes for removing the nitrogen compounds from middle distillates, including liquid–liquid extraction denitrogenation (L/L-EDN), ADN, oxidative denitrogenation (ODN), and others. ,− ADN has shown high efficiency and promise in removing nitrogen compounds from fossil fuels due to its nature, low cost, environmental friendliness, and sustainability. , The process is a favorable nitrogen reduction pathway as it can operate at very mild conditions without consuming hydrogen gas. Furthermore, it would be highly favorable to develop an optimal pretreating ADN process to remove nitrogen compounds selectively and thus improve the HDS reactivity of feedstock and enhance the overall performance of the existing hydrotreating unit.…”

“…The saturation adsorption capacity of MIL-101­(Cr) was 8.81 mg-N/g-ads at 3.5 h –1 liquid hourly speed velocity (LHSV) and 15.19 mg-N/g-ads at 0.8 h –1 LHSV. Recently, Meneses-Ruiz et al reported the ADN of an SRGO/LCO/CGO blend with 300 ppmw N over MIL-101­(Cr) in a packed-bed setup . They correlated the NRR with the treated amount of fuel per mass of adsorbent at different LHSV and found that LHSV had a significant effect on NRR.…”

“…For the same amount of the treated oil at 1.2 h –1 LHSV, the NRR was 82%, corresponding to the adsorption capacity of 3.45 mg-N/g-ads. Both of the studies in ADN over MIL-101­(Cr) , indicate that the diffusion of the nitrogen compounds in MIL-101­(Cr) pores can be one of the major problems that might limit its actual application, although MIL-101­(Cr) showed the high adsorption capacity for ADN. On the other hand, oil yield in the ADN process plays an important role in its commercial application in a refinery, as it is directly related to the refinery revenues.…”

“…Coker diesel (CD) from the vacuum residue coking process is one of the major middle distillates in petroleum refiners and is usually used as one of the hydrocarbon sources for increasing the diesel pool to improve the refining profit. However, CD usually contains high concentrations of coexisting nitrogen compounds, which can be up to several times higher than that in SRGO and even higher than that in LCO from fluid catalytic cracking (FCC). ,, Consequently, the ADN of coker diesel might be a greater challenge than the ADN of SRGO, LCO, and their blends. In the present study, the main aim is to explore an effective process for the ADN of coker diesel over a promising carbon-based adsorbent for a practical application in feedstock pretreatment to produce ULSD.…”