Qingfang Zha

The role of surface oxygen-containing functional groups in liquid-phase adsorptive denitrogenation by activated carbon

Abstract Twelve activated carbon (AC) samples with different physical and chemical properties were selected to investigate their ability for the adsorptive denitrogenation of liquid hydrocarbons using two model fuels containing typical nitrogen compounds, indole and quinoline in decane. The surface oxygen-containing groups of the ACs were characterized by temperature-programmed desorption with a mass spectrometer to identify and quantify the type and concentration of the oxygen-containing functional groups based on the CO- and CO2-evolution profiles. The adsorption behavior of AC for nitrogen compounds in decane was found to obey the Langmuir adsorption isotherm. The adsorption parameters (the maximum capacity and the adsorption constant) were estimated. With these results, the correlation between the adsorption performance of the AC samples and their physical/chemical properties was evaluated by a multiple linear-regression analysis, which indicated that the physical properties were not the key factors for the removal of the nitrogen compounds in decane. Furthermore, the oxygen-containing groups of ACs, especially the carboxylic acid groups, were found to be mainly responsible for nitrogen adsorption.

Carbon foam produced from fluid catalytic cracking slurry at atmospheric pressure

Abstract Pitch-based carbon foam containing pores of diameter 150–400 μm was produced from an intermediate pitch obtained from aromatic rich oil extracted from heavy oil FCC (fluid catalytic cracking) slurry by heating at atmospheric pressure. The effect of molecular weight distribution of the pitch on the formation of the foam was studied qualitatively. The variation of microscopic morphology, crystallite size, the interlayer spacing of microcrystal, and the density of the carbon foam carbonized from 800 to 1400 °C were also investigated. It was found that the wider the molecular weight distribution of the intermediate material, the worse the foam. Optical microscopy and scanning electron microscopy revealed that with increasing carbonization temperature, closed pores were opened and more pores were in twisted form. X-ray diffraction patterns indicated that the graphite microcrystal size decreased from 2.3 to 1.5 nm and their interlayer spacing increased from 0.3459 to 0.3477 nm below 800 °C. From 800 to 1400 °C, the graphite microcrystal size increased from 1.5 to 4.2 nm and the interlayer spacing decreased from 0.3477 to 0.3454 nm. The density of the carbon foams decreased form 0.52 to 0.16 g/cm 3 during the carbonization.

Retraction Note to: Microenvironment characterization for a novel biocompatible hybrid carbon-silicon material

The compatible carbon-silicon complex materials originated from precursor diglycerylsilane (DGS) and sugar-modified silane N-(3-triethoxysilylpropyl)gluconamide (GLS) have gained substantial popularity by demonstrating admirable properties to stabilize entrapped biomolecules. The microenvironment inside these materials, especially the distribution of sugar moieties inside the matrix, which is likely the most critical factor determining compatibility of these materials, still remains unclear. To deeply investigate the biocompatibility mechanism of these materials, we have adopted two different preparation routes for these materials by introducing GLS into the starting DGS sol stage, but things are different after the DGS gel is formed. A fluorescence probe rhodamine 6G is introduced herein in the DGS sol to monitor the distribution of GLS moieties, as well as the evolution of the microenvironment inside resulting materials. All in all, the findings demonstrated that the timing of GLS addition plays a critical role in controlling the evolution of the inner structure of materials, suggesting that this factor provides a promising route to tune the properties of the resulting materials.

Effect of Aromatic Enrichment on Reactivity of FCC Slurry

Abstract Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H-NMR), carbon-13 nuclear magnetic resonance (13C-NMR), and group compositional analysis were used to characterize the synthesis reaction of fluidized catalytic cracking (FCC) slurry before and after solvent extraction treatment. This investigation provided a great deal of critical information for use in future process development. Before solvent extraction, the FCC slurry is extremely complex. Saturates content is relatively high, and there are a variety of aromatic ring substituents. In addition, molecular uniformity is poor and chemical steric hindrance is strong. On the contrary, the composition of a fraction enriched in aromatics is relatively simple with excellent uniformity and homogeneous molecular alkyl-substituents. The aromatic enriched fraction (FCCRF) from the FCC slurry has weak chemical steric hindrance and, consequently, is more reactive than the original FCC slurry.