Study on Pd/CNT Catalyst for Selective Hydrogenation of α-β Unsaturated Aldehydes

摘要α-β不饱和醛选择加氢制备饱和醛的反应，不仅具有理论意义，而且具有实际应用价值。本文研究了Pd/CNT和Ni-Pd/CNT催化剂上，肉桂醛（CAL）选择加氢制备氢化肉桂醛的反应。取得的主要结果如下：1.经过氧化修饰处理的碳纳米管，负载Pd的效果优于未经处理的碳纳米管，前者还可以提高肉桂醛的转化率和氢化肉桂醛（HCAL）的选择性。2.以PdCl2为前驱物，用浸渍-氢气还原法和甲醛还原法制备了Pd/CNT催化剂，在对肉桂醛加氢反应的实验结果表明，两种方法制备的催化剂的主要产物都是氢化肉桂醛。而甲醛还原法制备的Pd/CNT催化剂的选择性更高，氢化肉桂醛选择性为89％。3.反应温度的升高和压力的增...ABSTRACTThe selective hydrogenation of α-β unsaturated aldehydes (UAL) containing C＝C and C＝O groups to the corresponding saturated aldehydes (SAL) remains a goal of considerable importance for both the industrial production in fine chemicals and the fundamental research in catalysis. In this thesis, the selective hydrogenation of cinnamaldehyde (CAL) to hydrocinnamaldehyde (HCAL) was studied over...学位：理学硕士院系专业：化学化工学院化学系_物理化学(含化学物理)学号：20032506

Selective Catalytic Hydrogenation of Cinnamaldehyde to Hydrocinnamaldehyde

采用煤质活性炭作载体,分别用HNO3、H2O2和(NH4)2S2O8进行预处理,然后用浸渍法负载PdCl2,在H2流中还原得到Pd/C催化剂,用于肉桂醛(CAL)选择加氢制氢化肉桂醛(HCAL)的反应。考查了Pd负载量,反应温度和压力对加氢反应的影响,优化了反应条件。进一步考查了助剂Fe、Co、Ni[1]对反应的影响。最终,CAL转化率为98%,HCAL选择性为88%。Coal-based activated carbon was pretreated with HNO_3,H_2O_2 and(NH_4)_2S_2O_8 before selected as support.A series of Pd/C catalysts were prepared by means of impregnation and with PdCl_2 as precursor.It was reduced in H_2 stream,and applied to selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde.Effects of Pd-loading,reaction temperature and pressure were discussed.In addition,promoters of Fe,Co,Ni were introduced to the catalysts.At last proper conditions for the reaction were found,and 88% selectivity to HCAL at 98% conversion of CAL was obtained.国家自然科学基金(No.20203014

Studies of the Mg-Al and Cation-Incorporated Hydrotalcites

研究了掺杂阳离子水滑石的制备及阳离子对水滑石性质的影响.分别制备了掺杂Zn2+、Ni2+、Fe3+型的水滑石,考察了掺杂阳离子对水滑石晶相结构、层间距、层间阴离子含量、水滑石表面形态、水滑石碱性的影响,结果表明,由于阳离子的引入,导致水滑石层间距减小及层间阴离子结合量降低,且使水滑石培烧产物电负性提高,并最终降低其碱性.以上述水滑石培烧产物作为固体碱催化剂促进苯甲醛和丙醛缩合,合成α-甲基肉桂醛,关联了水滑石培烧产物碱性与反应活性的关系.Mg-Al and cation-incorporated(containing Zn2+?Ni2+?Fe3+) hydrotalcites were synthesized and characterized. A detailed comparative analysis of structure and composition was made. Different cations influenced strongly textural parameters of hydrotalcites and the basicity of the obtained Mg-Al oxides after calcinations. With the cation incorporation, the distance of the brucite and the mount of CO2-3 as the compensating anion changed. Meanwhile the CO2-TPD was used to determine the basicity of the samples. The results showed that the basicity of the calcined hydrotalcites reduced. Finally, the activated hydrotalcite catalysts may efficiently replace homogeneous catalysts in Claisen-Schmidt condensation reaction of the benzaldehyde and propanal. And it was noteworthy that the calcined cation-type(containing Zn2+?Fe3+) hydrotalcites as catalysts did not show significant activity, in agreement with their low basicity.国家自然科学基金(20203014)资助项

Magnetic resonance image reconstruction using trained geometric directions in 2D redundant wavelets domain and non-convex optimization

Reducing scanning time is significantly important for MRI. Compressed sensing has shown promising results by undersampling the k-space data to speed up imaging. Sparsity of an image plays an important role in compressed sensing MRI to reduce the image artifacts. Recently, the method of patch-based directional wavelets (PBDW) which trains geometric directions from undersampled data has been proposed. It has better performance in preserving image edges than conventional sparsifying transforms. However, obvious artifacts are presented in the smooth region when the data are highly undersampled. In addition, the original PBDW-based method does not hold obvious improvement for radial and fully 2D random sampling patterns. In this paper, the PBDW-based MRI reconstruction is improved from two aspects: 1) An efficient non-convex minimization algorithm is modified to enhance image quality; 2) PBDW are extended into shift-invariant discrete wavelet domain to enhance the ability of transform on sparsifying piecewise smooth image features. Numerical simulation results on vivo magnetic resonance images demonstrate that the proposed method outperforms the original PBDW in terms of removing artifacts and preserving edges

Studies of the Mg-Al and cation-incorporated hydrotalcites

Mg-Al and cation-incorporated(containing Zn2+Ni2+Fe3+) hydrotalcites were synthesized and characterized. A detailed comparative analysis of structure and composition was made. Different cations influenced strongly textural parameters of hydrotalcites and the basicity of the obtained Mg-Al oxides after calcinations. With the cation incorporation, the distance of the brucite and the mount of CO32- as the compensating anion changed. Meanwhile the CO2-TPD was used to determine the basicity of the samples. The results showed that the basicity of the calcined hydrotalcites reduced. Finally, the activated hydrotalcite catalysts may efficiently replace homogeneous catalysts in Claisen-Schmidt condensation reaction of the benzaldehyde and propanal. And it was noteworthy that the calcined cation-type (containing Zn2+, Fe3+) hydrotalcites as catalysts did not show significant activity, in agreement with their low basicity

Synthesis of p-isopropyl Benzoic Acid Via Catalytic Oxidation of p-cymene

研究了在以冰醋酸为溶剂,以醋酸钴为催化剂条件下,原料配比、温度、压力等工艺条件对对异丙基甲苯氧化性能的影响.实验表明,当反应温度363~368 K,压力1.8~2.6 MPa,原料与溶剂质量比1:4~1:3时,可得到85%以上的对异丙基甲苯转化率和67.6%对异丙基苯甲酸收率;研究助剂Mn2+、Br-等对该反应氧化性能的影响,发现Co/Mn/Br-三元催化剂明显提高反应的选择性和产率.p-isopropyl benzoic acid,which is used as manufacturing intermediate for an anti-diabetes drug,Nateglinide,has been synthesized by selective oxidation of p-cymene.The direct oxidation of p-cymene in acetic acid by oxygen was catalyzed by cobalt catalyst system.The kinetic evaluations of catalytic reaction show that the oxygen pressure,reaction temperature,concentration of p-cymene and catalyst have remarkable influence on both conversion and selectivity of oxidation.67.6% yield of p-isopropyl benzoic acid is obtained after 2.5 h reaction at 365 K of p-cymene(25.%(mass) in acetic acid) under 2.6 MPa oxygen.Mn~(2+)、Br~-were introduced into the Co catalyst system as promoters.Although no improving effect is observed when these promoters were added separately,the Co/Mn/Br system,which contains both promoters,presents a significant stimulative catalytic performance for p-cymene oxidation.When the optimized catalyst composition of Co(OAc)_2,Mn(OAc)_2 and NaBr(1:2:1 molar ratio) is involved,the selectivity of p-isopropyl benzoic acid comes up to 83.2% at p-cymene conversion 88.5%,and an yield of 73.6% is obtained

The Effect of Varying Synthesis Methods on Mg-Al Hydrotalcite

用XRD、SEM及热重技术分析了共沉淀法、水热法、水合再生法制备水滑石的理化性质,结果显示水热法所得产品结晶度高,一次结晶粒径大,且表面规整度高,热稳定性好;而共沉淀法易造成结晶团聚,粒径分布范围大.根据水滑石的记忆功能发展而来的水合再生法,可以实现水滑石层间不同阴离子交换,表现出“智能”化的特性.Mg-Al hydrotalcites were synthesised by coprecipitation, hydrothermal and hydro-reconstruction methods.Detailed comparative analysis of structure and morphology were made by XRD,SEM and TG-DSC techniques.It had been found that the hydrothermal treatment elevated the hydrotalcite content and significantly improved the hydrotalcite crystallinity.Meanwhile a growth of hydrotalcite crystals and a remarkable decrease of surface area were observed after hydrothermal treatment.Since a strong agglomeration of primary particles occurred during preparation,the particle size of the samples synthesized by coprecipitation distributes in a wide range.Governed by a strong edge-surface platelet interaction,these aggregates gathered in a form so-called "sand rose morphology".XRD patterns and scanning electron micrographs revealed that rehydration of the samples calcined at 450℃ resulted in the reconstruction of the layered structure,owing to its "memory effect".国家自然科学基金(20203014)资

施肥对人工羊草地的产草量及养分吸收的影响

在人工羊草地上进行氮、磷、钾肥料实验,研究施肥对羊草产草量及养分吸收的影响.结果表明,肥料单施氮肥效果好,产草量达9.65t/hm~2,较不施肥增产2.75倍,较单施磷肥和钾肥增产71.0%和84.0%;肥料配施效果优于单施,氮、磷肥配施较单施氮肥和磷肥增产19.6%和105.3%,氮、磷、钾肥配施最好,产草量达14.11t/hm~2,较氮、磷肥配施增加16.5%,较单施氮、磷、钾肥分别增产26.6%,117.6%和122.7%.施肥可显著提高羊草对氮、磷、钾的吸收,单施氮肥羊草的氮、磷、钾的积累量分别较不施肥增加7.51,2.98,2.99倍;氮、磷、钾肥配施的养分积累量最高,氮、磷、钾较单施氮肥分别增加15.3%,27.9%和36.6%

施肥对人工羊草地的产草量及养分吸收的影响

在人工羊草地上进行氮、磷、钾肥料实验,研究施肥对羊草产草量及养分吸收的影响.结果表明,肥料单施氮肥效果好,产草量达9.65t/hm~2,较不施肥增产2.75倍,较单施磷肥和钾肥增产71.0%和84.0%;肥料配施效果优于单施,氮、磷肥配施较单施氮肥和磷肥增产19.6%和105.3%,氮、磷、钾肥配施最好,产草量达14.11t/hm~2,较氮、磷肥配施增加16.5%,较单施氮、磷、钾肥分别增产26.6%,117.6%和122.7%.施肥可显著提高羊草对氮、磷、钾的吸收,单施氮肥羊草的氮、磷、钾的积累量分别较不施肥增加7.51,2.98,2.99倍;氮、磷、钾肥配施的养分积累量最高,氮、磷、钾较单施氮肥分别增加15.3%,27.9%和36.6%

施用氮肥对人工羊草草地产量及养分吸收的影响

为研究施氮对人工羊草草地产量及养分吸收的影响.以中科2号羊草(Leyrnus chinensis‘ghongke No.2')为材料,设置5个氮肥处理水平,测定不同生育期羊草氮、磷、钾养分含量以及干草产量。结果表明:施用氮肥可以显著提高羊草产量,施用量以133.8 kg·hm~(-2)最为适宜,羊草产量为13134.7 kg·hm~(-2),每千克纯氮增产55.5 kg;施用氮肥可以提高羊草氮、磷、钾吸收量