Time filter

Source Type

Li X.,Tianjin University of Technology | Li Y.,Tianjin University of Technology | Li Y.,National Engineering Research Center for Distillation Technology
Catalysis Letters | Year: 2014

A novel type of Ce-Mo-Oxcatalyst prepared by the facile coprecipitation method has been utilized for the selective catalytic reduction of NO with NH3. The catalyst showed excellent activity, prominent resistant to the space velocity in a temperature range from 200 to 400°C and exhibited high SO2/H2O durability at 300°C. XRD and in situ DRIFTS proved that the strong interactions between CeOx and MoOx in the catalyst could be the main reason for the excellent NH3-SCR catalytic performance. © 2013 Springer Science+Business Media New York.


Li X.,Tianjin University of Technology | Li Y.,Tianjin University of Technology | Li Y.,National Engineering Research Center for Distillation Technology
Journal of Molecular Catalysis A: Chemical | Year: 2014

A series of MoO3 doped CeAlOx mixed oxide catalysts with different Mo/Al molar ratios were prepared by the simple coprecipitation method and used for selective catalytic reduction of NO with NH3. The Ce-Mo-AlOx catalyst with the Mo/Al molar ratio of 0.5 exhibited excellent activity and high H2O or/and SO2 poisoning resistance at 250 C. XRD revealed that the molybdenum oxide existed in either highly dispersed or amorphous phases on the catalyst surface. BET analysis results showed that the total pore volume and the average pore diameter of the CeAlOx catalyst was improved by the addition of MoO3. As determined by the H2-TPR and NH3-TPD, the redox capacity and total acidity of the CeAlOx catalyst were also enhanced by the introduction of MoO3, which are critical for the NH3-SCR reaction. The SCR reaction mechanism was also studied by the in situ DRIFTS, the coordinated NH3 and ionic NH4 + species together with the monodentate and bidentate nitrate were active intermediates on the CeMo0.5AlOx catalyst surface during the NH 3-SCR reaction. © 2014 Elsevier B.V.


Wang R.,Tianjin University of Technology | Li Y.,Tianjin University of Technology | Li Y.,National Engineering Research Center for Distillation Technology | Guo B.,Tianjin University of Technology | Sun H.,Nankai University
Energy and Fuels | Year: 2011

The desulfurization of fluid catalytic cracking (FCC) gasoline by alkylation over solid acid catalysts is considered to be a viable and less costly path to meet environmental regulations of sulfur emissions. However, side reactions in the process lead to significant levels of coke, which will greatly reduce the lifetime of the catalyst. In this paper, the catalytic mechanism of MCM-41 supported phosphoric acid catalyst for gasoline desulfurization by alkylation has been investigated by using experimental methods and quantum chemical calculations to study the catalytic behavior for the adsorption and reaction of different reactants, which can help optimize the reaction conditions and preparation methods of the catalyst for a more efficient alkylation process. The results showed that both the typical main and side reactions in the alkylation process started from a stable alkoxide intermediate that was formed by protonation of olefin adsorbed on the catalyst. Thiophenic compounds were more inclined to be adsorbed on the alkoxide intermediate than olefins for further reaction, and the activation energy for the alkylation of thiophenic sulfurs with alkenes was obviously lower than that for alkene oligomerization. Moreover, the thiophene alkylation was exothermic while the olefin oligomerization was endothermic. On the basis of these findings obtained by experimental and theoretical investigation, two methods that might be useful to further inhibit the occurrence of side reactions and improve the catalyst performance in the alkylation process were proposed. © 2011 American Chemical Society.


Guo B.,Key Laboratory for Green Chemical Technology of State Education Ministry | Bai J.,Key Laboratory for Green Chemical Technology of State Education Ministry | Li Y.,Key Laboratory for Green Chemical Technology of State Education Ministry | Li Y.,National Engineering Research Center for Distillation Technology | And 2 more authors.
Fluid Phase Equilibria | Year: 2012

Isobaric vapor-liquid equilibrium (VLE) data for the systems of 3-methylthiophene with four compounds (2,3-dimethyl-2-butene, n-heptane, toluene and 2-methylbutane) were measured at 101.33. kPa with a modified Rose-Williams still. Gas chromatography was used to analyze compositions of the samples from the vapor-liquid equilibrium systems. All the VLE measurements passed the thermodynamic consistency test proposed by Herington and showed positive deviations from Raoult's law. The experimental data of binary systems were correlated by Wilson model for the liquid phase and also compared with original UNIFAC and UNIFAC-Dortmund predictive models. Results showed that the original UNIFAC model gave better predictions than the UNIFAC-Dortmund model. © 2012 Elsevier B.V.


Wang X.,Key Laboratory for Green Chemical Technology of State Education Ministry | Li Y.,Key Laboratory for Green Chemical Technology of State Education Ministry | Li Y.,National Engineering Research Center for Distillation Technology
Fluid Phase Equilibria | Year: 2014

Isobaric vapor-liquid equilibrium (VLE) data of 2-ethylthiophene and n-octane binary system were measured at 101.33. kPa with a modified Rose-Williams still. Gas chromatography was used to analyze compositions of the samples from the vapor-liquid equilibrium system. The VLE measurement passed the thermodynamic consistency test proposed by Herington and no azeotropic behavior was found. The experimental data were correlated by Wilson, the non-random two-liquid (NRTL) and universal quasi-chemical activity coefficient (UNIQUAC) models, respectively. The corresponding parameters for the three models were obtained. Results showed that the Wilson model gave better predictions than NRTL and UNIQUAC models. © 2014 Elsevier B.V.


Wu M.,Tianjin University | Xu S.,Tianjin University | Xu S.,National Engineering Research Center for Distillation Technology | Zhao J.,Shenzhen Neptunus Bioengineering Holdings Co. | And 3 more authors.
Food Chemistry | Year: 2010

A process of depolymerization of a new fucosylated chondroitin sulphate from Thelenata ananas by free-radicals was developed. The fractions with different molecular weights and a narrow molecular weight distribution was obtained. The products were characterised by physicochemical properties, FT-IR spectra and NMR spectra. The results confirm the retention of primary structure of the fractions after the depolymerization. Furthermore, the anticoagulant activity of the fractions was evaluated by the activated partial thromboplastin time (APTT). The APTT activity decreases in proportion to the molecular weight following a logarithmic-like function, and the potentiating of prolongation of APTT activity requires at least an oligosaccharide chain of about 6-8 units (6000-7000 Da). Compared to high doses of low molecular weight heparin (LMWH), a more desirable molecular weight fraction (13,950 Da) demonstrates significantly lower anticoagulant activity. Thus, the fraction has more potential as an antithrombotic agent with reduced bleeding risk relative to LMWH. © 2010 Elsevier Ltd. All rights reserved.


Guo B.,Tianjin University | Wang R.,Tianjin University | Li Y.,Tianjin University | Li Y.,National Engineering Research Center for Distillation Technology
Fuel | Year: 2011

Gasoline desulfurization is receiving attention worldwide due to the increasing stringent regulations on sulfur content for environmental protection purpose. As conventional hydrotreating technology leads to significant octane number loss and processing costs, the gasoline alkylation desulfurization process, which consists of weighing down the sulfuric compounds by catalytic alkylation with olefins present in the feed and distillation followed by, is a rather attractive way. In this paper, firstly alkylation of thiophenic compounds was researched over macroporous sulfonic resin Amberlyst 35 in methanol presence to increase the selectivity of catalyst, then kinetics of thiophenic sulfurs alkylation in FCC gasoline was researched without and with methanol. Results found that appropriate methanol (≤2 wt.% methanol in model gasoline and ≤1 wt.% methanol in FCC gasoline) could inhibit olefins oligomerization significantly without influence on the conversions of thiophenic compounds. The alkylation of thiophenic sulfurs could be described as pseudo first order reaction regardless of the existence of methanol. The introduction of methanol decreases the reaction rate constant and increases the activation energy of alkylation reactions. © 2010 Elsevier Ltd. All rights reserved.


Guo B.,Tianjin University | Li Y.,Tianjin University | Li Y.,National Engineering Research Center for Distillation Technology
Chemical Engineering Science | Year: 2012

The increasingly stringent regulations on sulfur content in fuel require refineries to develop new desulfurization processes. Through the alkylation of thiophene and its derivatives with olefins followed by distillation, alkylation desulfurization is an alternative technology in the case of gasoline for its mild operation conditions and low loss of octane number. In this paper, the application of reactive distillation in gasoline alkylation desulfurization is studied, including a conceptual design and a rigorous steady state simulation. The conceptual design considers three aspects: thermodynamic analysis of the reactive system, benefits and constraints of the reactive distillation, and computation of the reactive residue curve maps. Results show that reactive distillation is feasible for gasoline alkylation desulfurization, and it has no constraints but great potential for its capital savings, improved conversion, reduced by-product formation, improved catalyst stability and avoidance of hot spots. The simulation results show that reactive distillation could obtain product gasoline with sulfur content less than 1. ppmw. It is shown that reactive distillation may be considered a viable technological alternative for gasoline alkylation desulfurization. © 2012 Elsevier Ltd.


Guo B.,Tianjin University | Wang R.,Tianjin University | Li Y.,Tianjin University | Li Y.,National Engineering Research Center for Distillation Technology
Fuel Processing Technology | Year: 2010

Sulfur removal has received increasing attention in recent years primarily for environmental protection purpose. As an attractive technology in the case of gasoline, OATS (olefinic alkylation of thiophenic sulfur) proposed to separate sulfur compounds by distillation after being weighed down by alkylation with olefins in the feed. In this paper, alkylation reactions of thiophenic compounds were studied over solid phosphoric acid catalysts (SPAM and SPAS using MCM-41 and Silicalite-1 zeolite as supporters respectively) and macroporous sulfonic resins (including NKC-9, D005-2 and Amberlyst 35) with model gasoline and FCC (fluid catalytic cracking) gasoline. Results showed that macroporous sulfonic resins showed better performance than solid phosphoric acid catalysts under milder conditions in both feeds. Among the resins, Amberlyst 35 was the most suitable catalyst for the application of catalytic distillation for its good performance at the temperature range of 353-413 K in FCC gasoline. However, the selectivity of isoamylene dimerization over Amberlyst 35 decreased with the temperature, which was harmful to the product yield and catalyst stability. Besides, different activity orders of solid phosphoric acid catalysts in model gasoline and FCC gasoline were explained by combining the acidic properties of the catalysts with the species of olefins in two feeds. © 2010 Elsevier B.V. All rights reserved.


Jiang B.,National Engineering Research Center for Distillation Technology | Yang X.,Tianjin University | Zhang L.,Tianjin University
Advanced Materials Research | Year: 2012

In this paper an artificial neural network (ANN) is used to correlate experimentally determined heat transfer rate of non-continuous helical baffle heat exchangers. First the heat exchangers with three helical angles were experimentally investigated under different inlet volumetric flow rate and temperature. The commonly implemented radial-basis function (RBF) neural network is applied to develop a prediction model based on the limited experimental data. Compared with correlations, the RBF network exhibits superiority in accuracy. The satisfactory results suggest the RBF network might be used to predict the thermal performance of shell-and-tube heat exchangers with helical baffles. © (2012) Trans Tech Publications.

Loading National Engineering Research Center for Distillation Technology collaborators
Loading National Engineering Research Center for Distillation Technology collaborators