Reverse Microemulsion Synthesis and Characterization of Nano Nickel Sulfide Catalyst for Residue Slurry-Phase Hydrocracking

Abstract

Nano nickel sulfide catalysts (NSCs) were successfully prepared for residue slurry-phase hydrocracking, which were synthesized by precipitation reaction in cetyltrimethylammonium bromide (CTAB) or mixed-surfactant (CTAB and Tween-80)/1-butanol/toluene/water reverse microemulsion in the presence of NiCl 2 as the nickel resource and (NH 4 ) 2 S as the sulfiding reagent. The prepared catalysts were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Experimental data revealed that both the kind and content of surfactants play a significant role in the morphology and size of NSCs. The particle size and crystallinity of NSC increased by thermal sulfiding at 300°C in Karamay vacuum gas oil (KLVGO). Optical micrographs showed that NSCs could be well-dispersed in Karamay atmospheric residue (KLAR) without obvious aggregation. On the basis of the lower yields of gas, atmospheric residue (AR), and coke, the NSCs showed higher catalytic activity than a conventional water/oil-soluble Ni catalyst. NSCs had excellent coke suppression performance (coke yield is less than 0.65 wt %), and the produced coke mainly dispersed in liquid products. With the decrease of NSC particle size, the coke suppression performance enhanced and the size of toluene-insoluble fraction in liquid products (TI-LP) decreased. NSCs provided location for coke generation and deposition during the slurry-phase hydrocracking process. The crystal form of NSCs dispersed in the TI-LP was Ni 3 S 2 , which was confirmed by XRD analysis.

Surface Modification of Nickel Sulfide Nanoparticles: Towards Stable Ultra‐Dispersed Nanocatalysts for Residue Hydrocracking

“…The TI yield of SZVR hydrocracking with CTAB‐NSNPs is 2.14 wt %, which decreases to 1.36 wt % for OS‐NSNPs and 1.57 wt % for DDT‐NSNPs (Figure a). According to the literature and our previous studies, in addition to acting as a dispersed hydrocracking catalyst, NSNPs also capture coke during the hydrocracking process . Subsequently, the morphology and size distribution of TI products from SZVR hydrocracking with different modified NSNPs were investigated.…”

“…During the hydrocracking reactions, the reaction pressure increased as high as around 18 MPa. At the end of the experiment, the hydrocracking products were separated into gas, naphtha, diesel, vacuum gas oil (VGO), VR, and TI products through a series of processes according to previous reports . The hydrogenation effect of the NSNPs was presented by light oil (naphtha and diesel) per coke ratio calculated by Equation (1): …”

“…In our previous study, nickel sulfide nanoparticles (NSNPs) with a non‐uniform diameter of 20–170 nm were synthesized by a precipitation reaction through a reverse microemulsion route . As a result of their small size and high dispersion compared to conventional water‐/oil‐soluble Ni catalysts, the synthesized NSNPs demonstrated excellent catalytic activity and anticoke performance in residue hydrocracking.…”

“…[16] Moreover, because of the high cost of Mo, several inexpensive transition metals,s uch as Ni, Co, and W, have been used to synthesize dispersed catalysts. [17,18] In our previous study,n ickel sulfide nanoparticles (NSNPs) with an on-uniform diameter of 20-170 nm were synthesized by ap recipitation reaction through ar eversem icroemulsion route. [17] As ar esult of their small size and highd ispersion compared to conventional water-/oil-soluble Ni catalysts, the synthesized NSNPs demonstratede xcellent catalytic activity and anticoke performance in residueh ydrocracking.…”

“…[17,18] In our previous study,n ickel sulfide nanoparticles (NSNPs) with an on-uniform diameter of 20-170 nm were synthesized by ap recipitation reaction through ar eversem icroemulsion route. [17] As ar esult of their small size and highd ispersion compared to conventional water-/oil-soluble Ni catalysts, the synthesized NSNPs demonstratede xcellent catalytic activity and anticoke performance in residueh ydrocracking. However, the used NSNPsd ispersed in toluene-insoluble (TI) products had asize less than 200 nm after the hydrocracking of Karamay atmosphericr esidue, which indicated that the small particles agglomerated because of the high surfacee nergy.As imilar result was obtained by Galarraga and Pereira-Almao for submicron multimetallic catalysts used in the hydrocracking of Athabasca bitumen at near in-reservoir conditions.…”