Guohe Que

Application of Co-Mo/CNT catalyst in hydro-cracking of Gudao vacuum residue

Abstract Carbon nanotube-supported Co-Mo catalysts with different Co/Mo atomic ratio were prepared by pore volume impregnation. These catalysts were used in the hydro-cracking reaction of Gudao vacuum residue, and the catalytic properties were compared with γ-Al 2 O 3 -supported Co-Mo catalysts under the same reaction conditions. It was found that the catalytic properties of Co-Mo/carbon nanotube (CNT) catalysts are inferior to Co-Mo/γ-Al 2 O 3 . However, the Co/Mo atomic ratio has great effect on the catalytic activity of Co-Mo/CNT; the Co-Mo/CNT catalyst with Co/Mo atomic ratio of 0.5 has the best catalytic properties, whereas for Co-Mo/γ-Al 2 O 3 catalyst the best Co/Mo atomic ratio is 0.35.

Interfacial adsorption of lipopeptide surfactants at the silica/water interface studied by neutron reflection

Lipopeptide surfactants are composed of amino acids and fatty acids and carry the inherent benefits of biocompatibility, degradability, functionality and easiness for structural design. In this work, the interfacial adsorption of a novel lipopeptide surfactant C14K1 has been examined by combining the measurements of spectroscopic ellipsometry (SE) and neutron reflection (NR). As for other model surfactants, the silicon oxide/water interface has been adopted to undertake the interfacial screening due to its readiness to facilitate the parallel measurements. SE revealed that the dynamic interfacial adsorption was characterized by an initial fast step within the first 2–3 min, followed by a slow relaxation step over the subsequent 30 min or so. Majority of the lipopeptide was found to adsorb with the fast initial step but the subsequent structural relaxation and adjustment led to the adsorption plateau. Interestingly, this pattern of dynamic adsorption is very different from amphiphilic peptides such as V6K1 and V6K2, but is similar to diblock copolymers bearing a hydrophilic MPC block and a pH responsive DEA block comprised of tertiary amine groups. Subsequent NR, in conjunction with deuterium labeling, revealed the formation of bilayer structure over a wide concentration and pH range, with the hydrophobic tails sandwiched in the middle and hydrophilic charged head groups projected outwards. The fully packed bilayer is some 40 A thick and changes in pH did not affect layer thickness much but did alter the packing density due to the different electrostatic repulsion associated with the charge dissociation of the head groups. Whilst surface adsorption of C14K1 behaved in many aspects like nonionic C12E6 (surface tension, salt effect and bilayer packing), detailed structural determination revealed little intermixing between the heads and tails, an observation different from C12E6.

Dynamic adsorption and structure of interfacial bilayers adsorbed from lipopeptide surfactants at the hydrophilic silicon/water interface: Effect of the headgroup length

Lipopeptides are an important group of biosurfactants expressed by microorganisms. Because they are well-known for being biocompatible, biodegradable, and highly surface active, they are attractive for a wide range of applications. Natural lipopeptide surfactants are however impure; it is hence difficult to use them for exploring the structure-function relation. In this work, a series of cationic lipopeptide surfactants, C(14)K(n) (n = 1-4), where C denotes the myristic acyl chain and K denotes lysine (Lys), have been synthesized, and their interfacial behavior has been characterized by studying their adsorption at the silicon/water interface (bearing a thin native oxide layer) using spectroscopic ellipsometry and neutron reflection (NR). The dynamic adsorption was marked by an initial fast step within the first 2-3 min followed by a slow molecular relaxation process over the subsequent 20-30 min. The initial rate of time-dependent adsorption and the equilibrated adsorbed amount showed a steady decrease with increasing n, indicating the impact of the molecular size, structure, and charge. NR revealed the formation of sandwiched bilayers from C(14)K(n), similar to conventional surfactants such as nonionic C(12)E(6) and cationic C(16)TAB. However, the electrostatic attraction between K and the silica surface caused confinement of the K groups, forcing the head segments into a predominantly flat-on conformation. This characteristic structural feature was confirmed by the almost constant thickness of the headgroup regions ranging from 8 to 11 Å as determined from NR combined with partial deuterium labeling to the acyl tail. An increase in area per molecular pair with n resulted directly from increasing the footprint. As a result, the hydrophobic back-to-back tail mixing and acyl chain tilting rose with n. The extent of chain-head intermixing became so intensified that the C(14)K(4) bilayer could be approximated to a uniform layer distribution.

Study on the mean dipole moments of Dagang atmosphere residue fractions

Abstract The mean dipole moments of Dagang atmosphere residue (DG-AR) fractions were investigated. DG-AR can be partitioned into six fractions: saturates and light aromatics, heavy aromatics, light resins, middle resins, heavy resins, and asphaltenes. The mean dipole moments of these fractions are 1.19, 2.88, 3.79, 4.92, 6.36, and 11.70 Debye, respectively, which increase from saturates and light aromatics to asphaltenes. This result is consistent with the differences in solubility of solvents used in liquid chromatography separation. The contents of hydrogen, carbon, nitrogen, and sulfur in each fraction were also measured. Opposite to the polarity, the H/C ratio of the residue fractions decreases from saturates and light aromatics to asphaltene. The ratios of S/C and N/C of the residue fractions vary in the same sequence of the mean dipole moment, which indicates that the hetero-atom content is a factor that influences residue polarity.

Effects of Fe/carbon black, Ni/carbon black catalysts on hydrocracking reaction of residual oil

Abstract The effects of the carrier carbon black on the interior hydrogen-transferring reactions of residual oil were studied in a miniature batch reactor. The results indicated that carbon black could promote the hydrogen transfer from tetralin to anthracene. Fe/carbon black and Ni/carbon black catalysts were prepared using equal volume impregnation method and characterized by X-ray diffraction and scanning electron microscope. The results showed that metal sulfides were attached on the surface of carbon black. The average diameter of metal sulfide crystals was about 1 μm. The thermal reactions of Karamay residual oil with carbon black, Fe/carbon black, or Ni/carbon black catalyst were carried out in a batch reactor in hydrogen atmosphere to investigate their effects which then were compared with those of traditional water-soluble dispersed catalysts. The reaction temperature was 430°C and the catalyst content was 1wt%. It was found that on coke formation restricting, water-washed catalyst was better than unwashed catalyst, Ni/carbon black was better than Fe/carbon black, and Fe/carbon black was better than water-soluble dispersed catalyst. The fraction distribution analysis of products showed that Fe/carbon black could restrict the cracking and condensation of residue.

Study on Colloidal Model of Petroleum Residues through the Attraction Potential between Colloids.

The samples of DaGang atmospheric residue (DG-AR), Middle East atmospheric residue (ME-AR), TaHe atmospheric residue (TH-AR), and their thermal reaction samples were chosen for study. All the samples were fractioned into six components separately, including saturates plus light aromatics, heavy aromatics, light resins, middle resins, heavy resins, and asphaltenes. The dielectric permittivity of the solutions of these components was measured, and the dielectric permittivity values of the components can be determined by extrapolation, which increased steadily from saturates plus light aromatics to asphaltenes. Moreover, the Hamaker constants of the components were calculated from their dielectric permittivity values. The Van der Waals attractive potential energy between colloids corresponding to various models could be calculated from the fractional composition and the Hamaker constants of every component. It was assumed that the cores of colloidal particles were formed by asphaltenes and heavy resins mainly; the other fractions acted as dispersion medium. For the three serials of thermal reaction samples, the Van der Waals attraction potential energy between colloids for this kind of model was calculated. For TH-AR thermal reaction samples, the Van der Waals attraction potential energy presented the maximum as thermal reaction is going on, which was near to the end of coke induction period.

Effects of active additives on Zeta potential of Lungu atmospheric residue

Abstract The effects of sodium dodecyl sulfonate (SDS), coconut amine (CA), and oleic acid (OA) on the Zeta potential, quantity of electric charge, granularity, and electric repulsive potential between the colloidal particles of Lungu atmospheric residue (LGAR) were studied with the help of the Plus Zeta potential analyzer and the 90Plus granularity analyzer. It showed that the three kinds of active additives could disaggregate asphaltene, and change the distribution of SARA four fractions, Zeta potential, quantity of electric charge, granularity, and electric repulsive potential between colloidal particles. The Zeta potential, quantity of electric charge and electric repulsive potential between colloidal particles first increased, and then decreased, whereas, the granularity of colloidal particles first decreased and then increased, with an increase in concentration of SDS and CA, and the extremum separately present to the mass fraction of 0.7% (SDS) and 0.5% (CA). OA can increase the Zeta potential, quantity of electric charge, and electric repulsive potential between colloidal particles, and decrease the granularity of colloidal particles. The magnitude of electric repulsive potential between colloidal particles is one of the main factors that restrain the aggregation of asphaltene.