Study On Rapid Mass Spectrometry Of Catalysts

The rapid development of modern chemical engineering is highly dependent on development of new catalysts,and selection of suitable catalysts is essential for reaction system.Although traditional catalyst characterization techniques such as electron microscopy,physical and chemical adsorption,X-ray diffraction,thermal analysis,electron spectroscopy,nuclear magnetic resonance,and infrared spectroscopy have been widely used in the characterization of catalysts.The steps are hindering and not suitable for rapid screening of catalysts.Because of its high sensitivity,good selectivity and strong specificity,mass spectrometry technique has been widely used in the field of food science,environmental protection,chemical industry and life science.However,there are few reports on the screening of catalysts.In this paper,a rapid mass spectrometry of catalyst characterization was carried out,and a mass spectrometry technique for rapid screening of catalysts was developed by systematically studying different copper catalysts using paper spray ionization-mass spectrometry.Specific research work includes the following aspects:In order to compare catalytic performance of different catalysts using a paper spray ionization source-mass spectrometry technique,a new method of simple catalyst coating on paper substrates was developed.The solid catalyst was uniformly coated on paper substrates surface,while the method has the advantages of simple operation,low cost,good repeatability and so on.The different types of solid catalyst can be uniformly coated on the surface of paper substrate by the method above,and for the aqueous solution soluble catalyst,the solution was loaded on the paper substrate surface by solution impregnation method.In order to systematically investigate the effect of preparation and mass spectrometry conditions on the catalyst screening,the effects of catalyst coating concentration,reaction time,reaction solvent and spray solvent on the stability and catalytic performance of catalyst coated paper were studied in detail.The effect of different types of copper catalysts on the formation of aniline in phenylboronic acid-ammonia reaction system was investigated by using paper spray ionization-mass spectrometry technique.The different types of copper catalysts in phenylboronic acid-ammonia system were screened by catalyst coated paper substrate method,Drop-Cast method and traditional reaction solution method respectively.It was found that theoptimal catalyst for the three methods was different under normal reaction time conditions.In order to further explore the differences between various methods,this paper examined the reaction kinetic curves of three methods that loaded to obtain the optimal reaction time of various methods.It was found that under the optimal reaction time conditions,catalyst coated paper substrate method was consistent with optimal catalyst for traditional reaction solution.At the same time,specific reason of the difference between the Drop-Cast method and catalyst coated paper substrate method was discussed.The screening of various copper catalysts in 4-biphenylboronic acid-ammonia reaction system by paper spray ionization source-mass spectrometry was studied.The reaction kinetic curves of 4-biphenylboronic acid-ammonia system were studied by using catalyst paper substrate coating method and traditional reaction solution method.The reaction kinetic curves of two methods above were explored and the corresponding optimal reaction time was acquired.It was found that catalyst coated paper substrate method was consistent with the best catalyst selected by traditional reaction solution method under the optimal time condition,which indicated that catalyst could be quickly evaluated by catalyst coated paper substrate method.The research of repeatability of catalyst coated paper substrate was investigated and the effect of catalyst mixed valence on catalytic reaction.The optimal elution solvent and elution efficiency of reaction products on the coated substrate were also investigated.At the same time,the color change of Cu2 O and CuCl2 coated paper on water-insoluble catalyst was observed with reasonably due to the influence of reaction solution and elution solvent.The effects of different copper catalytic activity on the number of cycles were studied.The efficiency of catalyst was performed and analyzed by paper spray ionization source-mass spectrometry method and physico-chemical properties of catalysts were characterized by X-ray photoelectron spectroscopy.It was found that a part of Cu catalyst of catalytic process changed high valence state,such as Cu2 O into CuO.In order to further confirm this conclusion,for the reaction system of phenylboronic acid and ammonia,these were investigated by CuO/Cu2 O,CuBr2/CuBr and CuCl2/CuCl catalytic system and single CuO,Cu2 O,CuBr2,CuBr,CuCl2 and CuCl.This observation demonstrated that in terms of a metal compounds behaved as catalyst,their mixed oxidation states [e.g.Cu(II)/Cu(I)] had a more pronounced effect than its single oxidation state(e.g.,Cu(II)or Cu(I))in the catalytic synthesis of organic compounds.