Preparation and Selective Hydrogenation Performance of MOFs Supported Pd Catalysts

Author:Yin Dong Dong

Supervisor:liang chang hai

Database:Doctor

Degree Year:2019

Download:131

Pages:133

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Selective hydrogenation of special unsaturated group play a key role in the synthesis of fine chemicals,and high selectivity is the main target during the designing and synthesis of catalyst.Supported noble metals are most-used catalyst in selective hydrogenation.The support isn’t isolated with noble metal nanoparticles.Both of the surface structure,acid-base property and containing characteristic group of support has an influence on the catalytic performance of metal nanoparticles.Comparing with the traditional support,the abundant pore and high surface area of MOFs is beneficial to the transfer of reactants and products.The frameworks of MOFs can be easily modified.The abundant metal sites can serve as Lewis acid,which will promote specific reaction.Herein,we have investigated the catalytic performance of MOFs loaded Pd catalysts in three kinds of selective hydrogenation reactions.Furthermore,the relation between catalyst structure and catalytic performance has also been studied.The main research contents and results are summarized as follows:We have successfully realized the immobilization of high dispersed Pd nanoparticles into MIL-101(Cr)using MOCVD method with the volatile Pd(rη3-C3H5)(η5-C5H5)is used as Pd precursor,which is prepared under the environment without water and oxygen.The Pd@MIL-101(Cr)catalysts exhibit better selectivity for 2-butene-1,4-diol than the Pd/MIL-101(Cr)and commercial Pd/C in the selective hydrogenation of 2-butyne-1,4-diol.The selectivity of 2-butene-1,4-diol can reach 94%with 100%conversion of 2-butyne-1,4-diol by using the as-prepared Pd@MIL-101(Cr).The encapsulation of Pd nanoparticles in the cavities of MIL-101(Cr)and the electron transfer from Pd nanoparticles to MIL-101(Cr)are beneficial to high selectivity of 2-butene-1,4-diol.Highly dispersed Pd nanoparticles are loaded into UiO-66-NH2 by a direct reduction in liquid after the adsoption of PdC142-on amino.This method is simpler than MOCVD method with good reproducibility.Different distribution state of Pd nanoparticles are formed when the Pd loading content is different on Pd@UiO-66-NH2.High selectivity of furfuryl alcohol(94%)is achieved using 0.5 wt%Pd@UiO-66-NH2 with complete consumption of furfural.Based on the high selectivity of furfuryl alcohol and L acid sites on UiO-66-NH2,the 0.5 wt%Pd@UiO-66-NH2 can serve as a bifunctional catalyst for the production of cyclopentanone(97%)at elevated temperature.The hydrogenation of C=C in furan ring is more difficult than C=0.While the high selectivity of tetrahydrofurfuryl alcohol(98%)can be reached using 4 wt%Pd@UiO-66-NH2 with complete consumption of furfural.We have introduced Au into Pd@UiO-66-NH2 to prepare Au-Pdx@UiO-66-NH2.The Au,Pd and UiO-66-NH2 can cooperatively boost the reductive amination of benzaldehyde with nitrobenzene for the production of N-benzylaniline.High selectivity for the hydrogenation of nitro is realized when Pd loading content is low(0.03 wt%),which benefit from the formation of Au-Pd with Pd dispersing on the surface of Au.Furthermore,the Lewis acid sites on UiO-66-NH2 can accelerate the reaction between benzaldehyde and aniline.A series of UiO-66(X)with different morphology and physical structure were synthesized with the introduction of different modulators.The Zr-O-Zr sites on the framework show excellent activity and high selectivity of cinnamyl alcohol in transfer hydrogenation of cinnamaldehyde.Coordinatively saturated UiO-66(HCl)with terephthalic acid is formed using HCl as modulator.But,the monocarboxylic acid molecules can replace the terephthalic acid and coordinate on the Zr sites.The UiO-66(PA)is a truncated octahedron particle with the introduction of propionic acid.The UiO-66(TFA)have the biggest surface area and pore volume,which is beneficial to the activation of cinnamaldehyde and isopropanol.The selectivity of cinnamyl alcohol is 97%when cinnamaldehyde is completely comsumed.