The Determination Of Tetrapropyl Ammonium Hydroxide Template And The Study Of Electrochemical Surface Behavior

Titanium silicon molecular sieve TS-1,which has superior catalytic performance in the catalytic organic oxidation and can effectively reduce the complex process flow and environmental pollution in the oxidation process,was widely used in the field of selective oxidation such as epoxidation of olefin,hydroxylation of aromatics,oxidation of alcohol amines,etc.The pore size of TS-1 was expanded to obtain hollow titanium silicalite(HTS-1),which were used to enhance the diffusion velocity of the molecules inside and outside the reaction molecule,thus improved its catalytic oxidation effect.In the synthesis of HTS molecular sieve,a large amount of waste liquid will be produced after the separation of the product from the mother liquid.The waste liquid contains a certain amount of templates,the direct discharge of mother liquor will wastes some available raw materials and pollute the environment,which is not conducive to the theme of environmental friendly development.This topic is mainly aimed at the determination of tetrapropylammonium hydroxide(TPAOH)and other elements in HTS mother liquor manufactured by in Hunan Jianchang petrochemical Co.Ltd.The method of quantitative analysis was explored for the utilization of mother liquor of special molecular sieve.The main contents are as follows:(1)A simple and rapid nuclear magnetic resonance internal standard('H-NMR)method was developed for quantitative determination of template in this molecular sieve waste liquid with D2O as solvent and CH3OH as internal standard.The effects of the vital instrument parameters on the integral area were investigated.The response linearity is ensured by linear regression correlation factors for TPAOH and TEAOH of R2=0.996 and R2=0.998,with good repeatability and high recovery,which can meet the requirements of industrial sample determination.(2)Cyclic voltammetry(CV)was used to study the electrochemical behavior of TPAOH on pretreated glassy carbon electrode.The effect of supporting electrolyte and scanning speed were investigated,it was found that the electrode reaction was diffusion-controlled quasi-reversible process.The possible mechanism of electrolysis and redox of TPAOH on the electrode surface was proposed.The inductively coupled plasma emission spectrometry(ICP-AES)was used to determine the titanium and silicon and other inorganic elements in the mother liquid.The silicon or other particle species in the mother liquid of the molecular sieve were detected by transmission electron microscopy,which could interfere with the redox reaction of TPAOH on the electrode.(3)Based on the conditions of cyclic voltammetry,the linear sweep voltammetry(LSV)method for the determination of TPAOH were studied.There is a piecewise linear relationship with R2=0.990 due to the effect of active sites and adsorption kinetics,the recoveries rate was 98.7%?109.7%,it is suitable for the determination of the sample of mother liquor.(4)The differences among Mohr method,potentiometric titration method and ion selective electrode method for the determination of chlorine ions in molecular sieve mother liquor were investigated.the study have shown that the results obtained by potentiometric titration are close to those obtained by Moire method and the potential titration directly determines that the mother liquid is not affected by pH and the type of electrode.The repeatability and recovery can meet the requirements of industrial analysis,while the ion selective electrode can not directly to determine the actual mother liquor samples.