Spherical Poly(vinyl imidazole) Brushes Loading Nickel Cations as Nanocatalysts for Aquathermolysis of Heavy Crude Oil

Abstract

Catalytic aquathermolysis in situ upgrading and reducing the viscosity of heavy oil in the reservoir remarkably enhances the recovery and is considered as a promising technology. However, the low catalytic efficiency and inferior dispersity in both water and oil limit its applications. In the present work, spherical polymer brush nanocatalysts were synthesized, in which nano-TiO2 is the core and poly­(vinyl imidazole) (PVI)-loading nickel cations are polymer brushes. The chemical characteristics, polymer-grafting content, nickel-loading content, and morphology of as-prepared catalysts were characterized by infrared (IR) spectroscopy, thermogravimetric analysis, inductively coupled plasma optical emission spectrometry, scanning electron microscopy, and transmission electron microscopy. The polymerization degree of PVI was analyzed by proton nuclear magnetic resonance (1H NMR) spectra. The effects of the nickel-loading content, catalytic conditions, and hydrogen donor on the viscosity of heavy oil were studied. The results show that the heavy oil is catalytically cracked by the synthesized catalysts, which leads to the reduction of oil viscosity. The viscosity reduction is enhanced by the increase of the nickel-loading content, catalytic temperature, dosage of catalyst, and hydrogen donor. The rheological behaviors in terms of flow curve, thixotropy, viscoelasticity, and time dependence of cracked oil were studied. To explore the cracking mechanism, the four compositions of heavy oil before and after aquathermolysis were compared. The extracted asphaltenes and resins were further analyzed by elemental analysis, 1H NMR spectra, and IR spectroscopy. The organic compounds in reacted water were characterized by gas chromatography–mass spectrometry. It is found that the content of light saturates is much increased after aquathermolysis, along with the distinct decrease of resins. From the structure change of resins, such as the decrease of hydrogen/carbon and methylene/methyl ratios and increase of aromaticity and aromaticity condensation, the increased light saturates are due to the dissociation of alkyl side chains in resins. In addition, the aromaticity and aromaticity condensation in asphaltenes are found decreased, which is because of the fragmentation and depolymerization of large aromatics. Meanwhile, the loss of oxygen in both asphaltenes and resins is connected with the phenols found in the reacted water, indicating the breakage of the C–O bond and heteroaromatic ring-open reaction in both asphaltenes and resins during aquathermolysis.

In-Situ Heavy Oil Aquathermolysis in the Presence of Nanodispersed Catalysts Based on Transition Metals

“…In work [84], spherical polymer brush nanocatalysts were synthesized, in which nano-TiO 2 is the core and poly(vinyl imidazole) (PVI)-loading nickel cations are polymer brushes. A group of scientists generated MoWNi-sulfides in-situ by thermal decomposition of metalpolymer precursors based on a co-polymer of polymaleic anhydrides in hydrocarbons [85].…”

Sustainability Effect of Water Gas Shift Reaction (Syngas) in Catalytic Upgrading of Heavy Crude Oil and Bitumen

“…Hydrogen can be supplied directly as a pure gas [17][18][19][20], produced in-situ from chemical compounds and biological species [21][22][23][24], or extracted from syngas process in-situ via water gas shift reaction [20,[25][26][27][28]. In the first case, a significant amount of hydrogen proceed to hydrogen sulfide (H 2 S) [18,20] and the process is over the odds [19].…”

“…The impediment of the second method is low conversion [22] and inability to operate at relatively higher reaction conditions due to biological species [23,24]. However, supply of hydrogen via syngas is inexpensive [25], has high conversion rate [26][27][28] and the reaction could be operated between low water gas shift reaction (200-350°C) [28,29] and high water gas shift reaction conditions (350-450°C) [20,27]. In addition, higher upgrading has been reported with processes where hydrogen was obtained via syngas to pure hydrogen gas [26].…”

“…In heavy crude oil and bitumen upgrading where the hydrogen is supplied from syngas, the source is usually from water in-situ [13] or introduced into the reactor alongside feedstock [20,[25][26][27][28][29][30][31]. Irrespective of the method of providing water, the reactor would be pressurized in a neutral environment, usually nitrogen to mimic reservoir conditions.…”

Poly(1-vinylimidazole) grafted on magnetic nanoparticles - attainment of novel nanostructures

“…In the literature are many papers reporting about the covering of magnetite with PVIm, but they are using as a polymerization initiator a silica derivative able to initiate the polymerization of VIm at the magnetite surface. [12][13][14][15] The main purpose of this study is the synthesis of new MNPs covered with poly(1-vinylimidazole) (PVIm) shells starting with MNPs coated with bis [2-(methacryloyloxy)ethyl] phosphate as stabilizer capable of joining the polymerization of 1-vinylimidazole (VIm) by means of their C=C double bonds. Poly(1-vinylimidazole) is chosen to graft on nanosized magnetic particles, as the resultant MNP-PVIm are anticipated to expand their application.…”