金属有机骨架(MOFs)多孔复合材料的制备及吸附脱硫性能研究

摘要

在世界经济发展过程中，化石燃料在许多国家能源领域的发展中发挥了重要作用并且在世界范围内它们仍然领先其他能源。从全球的角度来看，目前液体燃料被视为许多行业发展的一个重要的驱动力，例如航空运输，海洋运输，铁路和公路运输，工业生产流程等。当然，这些液体燃料包含有毒的有机含硫化合物，这些化合物含硫量很高，高含硫量的液体燃料也严重威胁全球环境安全，这是因为硫的燃烧导致有毒的硫氧化物(SOx)逐渐释放在大气中，并进一步形成酸雨污染环境或者在大城市生成很大的交通烟雾。
　　在过去的几十年里，已经有很多研究者使用多孔材料、沸石、活性炭等用于液相脱硫实验，目标在于找到更好更合适的液体燃料脱硫技术。近年来，已经有研究表明在大气压力和环境温度等比较温和的条件下金属有机框架(MOFs)用于液体燃料的吸附脱硫具有很好的性能。因此，从这个方面而言，液体燃料的吸附脱硫不仅操作简单，而且成本较低，为此找到合适的MOFs材料并应用于吸附脱硫具有很大的潜力。在水热或者溶剂热条件下，使用铕和铜作为金属离子中心，1，3，5-均苯三甲酸(H3BTC)作为有机配体合成了铕金属有机框架(Eu-MOF)和Cu-BTC，并且对合成的MOFs使用X射线衍射(XRD)、傅里叶红外变换(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和Brunauer-Emmett-Teller(BET)等表征方法对MOFs材料的结构进行了表征。同时，以噻吩/正辛烷溶液作为含硫模拟油，研究了合成的Eu-MOF和Cu-BTC的吸附脱硫性能。结果表明，在吸附剂的最佳脱硫条件下，即模拟油和吸附剂的质量比是100∶1，温度为30℃的条件下，Cu-BTC和Eu-MOF的最大吸附脱硫能力分别为27.43mgS/gMOF和24.59mgS/gMOF。
　　为了提高和改善传统的Cu-BTC的吸附脱硫性能，本文将Cu-BTC与γ-Al2O3、粘土(Clay)和活性炭(AC)等多孔载体材料复合，制备了金属有机骨架(MOFs)和多孔载体结合的复合材料。如采用水溶剂热方法分别合成了Cu-BTC质量分数为30％，40％和50％的Cu-BTC/γ-Al2O3、Cu-BTC/Clay和Cu-BTC/AC复合材料。新合成的复合材料使用先前的表征方法:X射线衍射(XRD)、傅里叶变换(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和Brunauer-Emmett-Teller(BET)对复合材料的结构进行了表征。表征结果表明，Cu-BTC多孔复合材料保持了典型金属-有机骨架材料Cu-BTC的特征，同时，Cu活性位点在载体上的高度分散性改善了Cu-BTC复合材料的吸附脱硫性能。
　　基于之前实验条件优化结果，本文在温和的条件下进行反应，研究了MOFs复合材料的脱硫吸附性能，即对噻吩/正辛烷模拟油中噻吩的吸附脱除，实验结果表明，相比其他的MOFs复合材料，Cu-BTC/γ-Al2O3复合材料有更好的吸附脱硫性能。这表明在Cu-BTC制备过程中加入载体，可以进一步提高了催化剂从噻吩/正辛烷中吸附去除噻吩的吸附脱硫性能。在温度为30℃的反应条件下，模拟油/吸附剂比为100∶1，脱硫6小时后，最大吸附率达到78％，对于40％Cu-BTC/γ-Al2O3催化剂的吸附容量为29.71mgS/g。在同一脱硫条件下，40％Cu-BTC/Clay和50％Cu-BTC/AC的吸附脱硫率分别达到76％和74％，40％Cu-BTC/Clay的吸附容量是28.95mgS/g而50％Cu-BTC/AC达到28.19mgS/g。
　　本文还研究了吸附脱硫性能较高的样品的重复使用性和吸附动力学行为。结果表明MOFs和MOFs复合材料在连续使用5次后，依然具有较高的脱硫吸附性能。从吸附动力学的研究结果上看，拟一级和拟二级速率方程用来代表Eu-MOF，Cu-BTC和Cu-BTC多孔复合材料的吸附动力学行为都具有很好的相关性。然而40％Cu-BTC/γ-Al2O3的对于吸附噻吩行为更适合于拟一级动力学模型。

目录

声明

ABSTRACT

摘要

CONTENTS

Chapter 1 Introduction and literature review

1．1 Purpose and signiacance of the study

1．2 Progress in the development of adsorptive desulfurization

1．2．1 Hydrodesulfurization(HDS)

1．3 Porous materials

1．4 Metal Organic Frameworks(MOFs)

1．4．1 Structure of MOFs

1．4．2 Analogous MOFs

1．4．3 Methods of synthesis of MOFs

1．4．4 Functionalization of MOFs

1．5 Applications of MOFs

1．5．4 Application of MOFs in adsorption desulfurization

1．6 Research methodology and main content

Chapter 2 Experimental section

2．1 Introduction

2．2 Materials and equipment facilities

2．2．1 Materials for experiments

2．2．2 Facilities for the experiments

2．3 Synthesis of MOFs

2．4 Synthesis of MOF／porous composite materials

2．4．2 Synthesis of Cu-BTC／Clay composites

2．5 Characterization of MOFs and MOF／composite materials

2．5．1 XRD characterization

2．5．4 N2 adsorption-desorption isotherms

2．6 Preparation of model oil solutions

2．7 Evaluation of adsorption desulfurization performance of MOFs and MOFs composites

2．7．2 Analysis of samples and data processing

Chapter 3 Structure of Eu-MoF and Cu-BTC and their performance in Adsorptive desulfurization of model oil

3．2．1 Characterizations of Eu-MOF

3．2．2 Evaluation of adsorption desulfurization performance of Eu-MOF

3．2．3 Adsorption kinetics behavior of Eu-MOF

3．3 Characterization and adsorption desulfurization performance of Cu-BTC MOF

3．3．1 Characterization of Cu-BTC MOF

3．3．2 Evaluation of adsorptive desulfurization performance of Cu-BTC MOF

3．3．3 Study of adsorption kinetics of Cu-BTC MOF

3．4 Summary

Chapter 4 Structural characterization of Cu-BTC／γ-Al2O3 composite materials and their adsorptive desulfurization performance for removal of thiophene from model oil

4．1 Introduction

4．2 Characterization of Cu-BTC／γ-Al2O3 composites

4．2．3 Study of crystalinner structure of Cu-BTC／γ-Al2O3 composites

4．2．4 Study of surface area and pore structure of Cu-BTC／γ-Al2O3 composites

4．3 Adsorptive desulfurization performance of Cu-BTC／γ-Al2O3 composites

4．3．2 Innuence of adsorption temperature

4．3．3 Effect of model oil／adsorbent mass ratio

4．3．4 Reusability of Cu-BTC／γ-Al2O3 composite materials

4．4 Study of adsorption kinetics of Cu-BTC／γ-Al2O3 composites

4．5 Summary

Chapter 5 Cu-BTC／Clay composite materials in adsorption desulfurization of model oil and related calculation of kinetics

5．1 Introduction

5．2．2 Functional groups analysis in Cu-BTC／Clay composites

5．2．3 observations of core-shell structure in Cu-BTC／Clay composites materials

5．2．4 Effect of bentonite clay on surface area and pore size of Cu-BTC

5．3 Evaluation of performance of Cu-BTC／Clay composite materials

5．3．1 Effect of Cu-BTC content

5．3．2 Effect of adsorption temperature

5．3．3 Effect of model oil／adsorbent mass ratio

5．3．4 Reusability of Cu-BTC／Clay composite materials

5．4 Study of adsorption kinetics of Cu-BTC／Clay composite

5．5 Summary

Chapter 6 Structure Characterization of Cu-BTC／AC composite materials in adsorptive desulfurization process and its absorption kinetics

6．2 Characterization of Cu-BTC／AC composite materials

6．2．2 Structure and functional group behavior in Cu-BTC／AC composites

6．2．3 Observations of internal structure of crystal size in Cu-BTC／AC composites

6．2．4 Effect of activated carbon on the surface area and pore structure of Cu-BTC／AC composites

6．3 Investigation of adsorptive desulfurization performance of Cu-BTC／AC composites materials

6．3．2 Effect of adsorption temperature

6．3．3 Effect of model oil／adsorbent mass ratio

6．3．4 Reusability of Cu-BTC／AC composite materials

6．4 Study of adsorption kinetics of Cu-BTC／AC composite materials

6．5 Summary

Chapter 7 Conclusions and outlook

7．1 Conclusions

7．2 Outlook

References

Acknowledgements

Publications

Author’s resume

Advisor’s resume