Showing papers in "Natural Gas Chemical Industry in 2014"

Stripping ammonia nitrogen wastewater in a novel rotating packed bed

Abstract: The rotor structure of the novel rotating packed bed(RPB) is nested packing rings, which is a new efficient apparatus for intensifying the gas-side mass transfer resistance controlled process. Ammonia-nitrogen wastewater was stripped by air in the novel RPB, and the effect of gas-liquid ratio, pH value, high-gravity factor and the number of cycles on were studied experimentally.The results showed that the single-stage removal rate of ammonia-nitrogen was 43.87% under following operational conditions:temperature of 10℃, gas-liquid ratio of 1000, pH value of 11.0, high-gravity factor of 67, and the removal rate of ammonia-nitrogen could reach 80.2% and 90.1%, respectively, after 4 and 8 cycles. The removal rate of ammonia-nitrogen in the novel RPB was much higher compared with that of the cross-flow RPB, which indicated that the novel RPB could intensify effectively the gas-side mass transfer resistance controlled process.

Study on thermodynamics of propylene dimerization to 4-methyl-1-pentene

Abstract: The standard molar enthalpy of formation, standard entropy and isobaric molar heat capacity of propylene dimerization products were estimated by using Benson group contribution method and ABWY method. The enthalpy change, Gibbs free energy change and equilibrium constant of propylene dimerization to 4-methyl-1-pentene reaction system were calculated in detail as a function of the temperature from 298K to 700K. The thermodynamic equilibrium and the limit of different reaction steps were analyzed. The thermodynamic possibility and formation sequences of propylene dimerization reaction system were also judged. The effects of temperature and pressure on the equilibrium conversion were investigated. The equilibrium conversions of propylene dimerization reactions in the specific process condition were obtained according to thermodynamic calculations. The results showed that propylene dimerization is an exothermic reaction, which is spontaneous at low temperature and can reach to a deep extent. Low temperature and high pressure are favored to propylene dimerization to 4-methyl-1-pentene reaction from a thermodynamic point of view. The occurrences of the other side reactions are easier than propylene dimerization to 4-methyl-1-pentene except to 1-hexene. The appropriate process conditions are 400K-450K, 8MPa-15MPa. The equilibrium conversions of all propylene dimerization reactions approach 100% at 428K, 10MPa.

Effect of shape-forming method on performance of ZSM-5 molecular sieve catalyst for MTP

Abstract: Using HZSM-5 molecular sieve with high Si/Al ratio as active component and SiO2 or γ-Al2 O3 as binder to prepare the catalysts for methanol to propylene(MTP) by extrusion The catalytic performances of the prepared catalysts were evaluated under the common conditions for MTP reaction, and XRD, NH3-TPD, Py-IR etc were used to characterize the catalysts to investigate the effect of different binders on the catalytic activity and mechanical strength of the catalysts The results showed that the binders had obvious effect on the strength and surface acid behaviour of the catalysts as well as the distribution of MTP products, and SiO2 demonstrated a better selectivity to light alkenes and a higher stability than γ-Al2 O3

Study on desorption properties of single amine and mixed amines in natural gas decarbonization process

Abstract: The desorption properties of five kinds of amines MEA, DEA, TEA, DETA, TETA and their mixed amines with MDEA in the process of CO2 removal from natural gas were analyzed by the comparative experiments. The change regulation of desorption rate of different types of single amine and mixed amines was investigated. The results showed that the desorption properties of two kinds of enamines DETA, TETA and their mixed amines with MDEA were relatively poor. While the desorption properties of the above amines could be improved by increasing the absorption saturation.

Review of octane number prediction methods for gasoline components and gasoline

Abstract: The prediction methods of octane number for gasoline components and gasoline were introduced. The focus was on using the topological index method and group contribution method to study the quantitative structure-property relationship(QSPR) of octane number of gasoline components and using the parameters extracted by instrument to study QSPR of octane number of gasoline. The advantages and disadvantages of various methods employed for fitting, including artificial neural network, genetic algorithm, support vector machine, multiple linear regression and partial least squares, were analyzed. Topological indices had relatively simple calculation process and could more completely represent the molecular structures, and the relevance of the prediction model produced by it was better than those by other methods. Therefore, topological index method was most widely used.

Advances in catalysts and their deactivation for oxidative carbonylation of methanol to dimethyl carbonate

Abstract: Heterogeneous copper catalysts used for liquid-phase and vapor-phase oxidative carbonylation of methanol to dimethyl carbonate were reviewed, including supported CuCl/CuCl2catalysts, low-chlorine copper catalysts prepared by solid-state ion exchange and chlorine-free copper catalysts Furthermore, the deactivation reasons of these catalysts in liquid-phase and vapor-phase reactions were analyzed and summarized The deactivation of catalysts was mainly due to the by-product water not being removed timely in liquid-phase reaction, and due to the loss of chlorine ion, sintering and carbon deposition in vapor-phase reaction