Basic Study On The Application Of Copper-modified Sorbent For Adsorption-oxidation Of PH₃

As a typical highly toxic gas,the emission and distribution of PH₃ have significant industrial and regional characteristics.Because of the strong chemical activity and comprehensive biological toxicity,the direct emission of PH₃ into the atmosphere will pose a serious threat to human health and the environment.Therefore,PH₃ must be effectively removed.The supported sorbents prepared by loading copper species on the porous support can realize the removal of PH₃ in the exhaust gas by adsorption-oxidation.However,the PH₃breakthrough capacity of conventional supported sorbents is limited,and the reaction mechanism of PH₃ on its surface still needs to be further clarified.In addition,there are few related studies on the reuse of deactivated sorbents.Motivated by the above,this thesis carried out related research,aiming at developing high-performance PH₃ sorbents.Meanwhile,the resource conversion of PH₃ is realized through the development of the potential value of the deactivated sorbent,which provides an experimental and theoretical basis for the efficient purification of highly toxic gas PH₃ and its resource conversion technology.The main research contents and research results are as follows:（1）The Cu/HZSM-5 sorbent was prepared by the impregnation method,and it was found that the adsorption and removal performance of Cu/HZSM-5 sorbent under low temperature and low oxygen conditions could be significantly improved by doping a trace amount of Ce.Experimental results showed that doping with 1 wt%of cerium(Ce₁Cu₃₀O_X/HZSM-5)can significantly improve the performance of the sorbent.The PH₃breakthrough capacity was identified as 114.36 mg（PH₃）·g^-1_sorbent.Further research found that Ce doping can effectively increase the specific surface area of the sorbent,and at the same time improve the oxidative properties of the adsorbent and the dispersion of active components.In addition,after three thermal regeneration cycles,the sorbent still has ideal performance.（2）To solve the problem of high cost and low PH₃ capacities of Ce₁Cu₃₀O_X/HZSM-5sorbent,activated carbon was used as support,and a high-performance PH₃ sorbent（3DCu1/CBAC-350）with a three-dimensional structure of active components was successfully prepared by hydrothermal synthesis method.The optimal sorbent showed the highest PH₃ breakthrough capacity of all the sorbents tested(181.41 mg（PH₃）g^-1_sorbent).The excellent performance of the sorbent is attributed to the unique three-dimensional spatial structure,large specific surface area,and abundant surface-active oxygen of its active components.The practical advantage of this 3D sorbent lies in the conversion of the active components into the high value-added P-type semiconductor Cu₃P after the deactivation of the sorbent.After testing,the deactivated sorbent exhibited obvious photocatalytic activity.On this basis,this study proposes a PH3 disposal strategy:using a copper-modified sorbent to convert the PH₃ pollutants in the exhaust gas into a recyclable Cu₃P photocatalytic material under mild conditions.（3）To solve the problem of the complex preparation process of 3DCu1/CBAC-350 and further improve the performance,combined with the preparation method of the photocatalytic material g-C₃N₄,an NC-doped Cu O sorbent（Cu O@NC）was prepared.The design of the sorbent is guided by the resource conversion of PH₃,as well as realizing high-efficiency purification and removal of PH₃.The results show that the abundant oxygen vacancies on the surface of the sorbent prepared by the simple method are beneficial to the dissociation of O₂,which in turn promotes the dissociative adsorption and conversion of PH₃,thus showing superior PH₃ removal performance,and the breakthrough capacity is 272.54mg（PH₃）g^-1_sorbent.More importantly,after the deactivation of the sorbent,the active component Cu O can be converted into high-purity Cu₃P,which not only realizes the efficient purification of PH₃ but also realizes the resource utilization of PH₃.The deactivated sorbent has excellent photocatalytic performance for photocatalytic degradation of rhodamine B（Rh B）in a liquid phase,which is found to be stronger than most of the reported photocatalysts after normalizing the reaction conditions.（4）The kinetic model of power function was used to numerically fit the breakthrough curve of 2Cu O@NC sorbent,and the kinetic equation of PH₃ adsorption-oxidation was obtained by analyzing and fitting a series of kinetic experimental data.Meanwhile,the reaction rates measured experimentally under different conditions were compared with the reaction rates calculated by the reaction kinetic equation,and it was found that the relative error between the theoretical value and the actual value was less than 5%,indicating that the obtained equation was reliable and could be applied to such a fixed bed.In addition,the reaction mechanism of PH₃ on the Cu O（111）crystal plane was investigated by molecular simulation calculations.The results show that on the reducing surface OV-Cu O（111）,PH₃can be stably adsorbed at the oxygen defect.PH₃ generates P species through a stepwise dehydrogenation process（PH₃*→PH₂*→PH*→P*）.The reducing surface can promote the dissociation of O₂,which makes some adsorbed oxygen on the surface of Cu O.This adsorbed oxygen on the surface can be removed by gradual hydrogenation to produce H₂O,to restore the perfect surface...