钯催化CO/C₂H₄共聚动力学研究

【作者】 陈永城；

【导师】 陈樑；

【作者基本信息】 昆明理工大学 ， 应用化学， 2007， 硕士

【摘要】 “人与自然的和谐发展”是21世纪的主题，在全球资源短缺和气候日益恶化的今天，环境友好材料受到了世界各国的青睐。聚酮是一种具有交替共聚结构和高结晶度的可光降解的热塑性工程高分子材料，不仅具有熔点高、机械性能好、耐磨性、耐化学药剂性、耐热性、气体阻隔性等优良的物理特性，而且聚酮主链上大量存在的羰基赋予其优良的光降解性。因此，利用化工冶金等行业生产过程排放的含一氧化碳废气通过净化，获得价廉的一氧化碳合成这种性能优良的绿色环保材料，已成为一碳化工的重要研究课题。本研究给合云南省丰富的CO资源，采用Pd（AcO）₂DPPP为催化前体，对钯催化CO／C₂H₄共聚工艺参数进行了优化，考察了搅拌速率、催化剂浓度、反应温度、反应压力、原料气组成和酸等对共聚速率的影响，确定了适宜的聚合工艺条件：搅拌速率为750r／min，催化剂浓度为0.06mmol／L，反应温度为95℃，反应压力为4.0MPa，CO：C₂H₄=1：1，H₂SO₄：Pd=100。研究用FT-IR、¹H-NMR和¹³C-NMR技术对自制聚酮产品进行结构分析，发现聚合物中的主要结构是—（CH₂CH₂CO）_n—，并存在少量的—CH₂CH₂CH₂CH₂CO—，其端基结构为酮式端基和酯式端基，其中酮式端基稍多一些。根据自制聚酮结构的分析对钯催化CO／C₂H₄共聚的链增长过程机理做出合理的假设，并推导出一系列的动力学方程，利用不同压力和不同反应气组成的实验数据对方程的动力学参数进行回归，最终建立了钯催化CO／C₂H₄共聚的动力学模型：r=k₂k₄K₁α_Aα_B[Pd]/（k₄+k₄K₁α_A+k₂K₁α_B）其模型计算值与实验值能够良好地符合，该模型可以描述钯催化CO／C₂H₄在甲醇中共聚的动力学行为。综合聚酮的结构分析和动力学研究，本论文首次提出了钯催化CO／C₂H₄在甲醇中共聚的链增长机理是由两个循环组成的，即CO／C₂H₄交替插入的主循环和C₂H₄连续插入的辅循环。更多还原

【Abstract】 Polyketone （poly-3-oxotrimethylene）, alternating copolymer of ethylene and carbon monoxide is a novel semicrystalline thermoplastic high-performance polymeric materials. It offers a broad range of features: outstanding chemical resistance and low permeability; superior strength, wear and friction characteristics, high resistance to fatigue, creep, swelling and repetitive deformation; excellent balance of stiffness and toughness over a wide temperature range; high-quality moldings at short cycle times; resistance to a variety of fuels, organic solvents and aggressive aqueous media; halogen/red phosphor-free flame retardancy. The carbonyl groups contained in polymer backbone abundantly make the material photodegradable. Also, the carbonyl group can be used for derivation to a variety of interesting new materials. The base materials are readily available; furthermore, considerable CO can be regained from industrial exhaust gases of chemistry & metallurgy. In the latest years, it is an important task in CO chemistry taking advantage of industrial exhaust gases contained abundant CO to synthesize polyketone.In the paper, Pd（AcO）₂DPPP was adopted as catalytic precursor in CO/C₂H₄ alternating copolymerization. Synthetical process of copolymerization were optimized by deliberate investigation of reaction conditions, including agitation speed, catalyst concentration, reaction temperature, reaction pressure, monomers composition and acid etc. Then fitter process conditions were gained: agitation speed=750r/min, [Pd]=0.06mmol/L, T=95℃, P=4.0MPa, CO:C₂H₄=1:1, H₂SO₄:Pd=100.The structure and properties of polyketone were characterized by ¹H-NMR,¹³C-NMR and FT-IR, and it was found polyketone was linear alternating copolymer of ethylene and CO, its backbone chain was made up of constitutional unit, — CH₂CH₂CO —, in its ¹³C-NMR spectrum, some thimbleful fragments, — CH₂CH₂CH₂CH₂CO—, were found out. The structures of end-groups were proved to be — COOCH₃ and—COCH₂CH₃.On the ground of the above experimental & analytical results, series of logical assumptions of chain propagation were set, and corresponding kinetic equations wereevaluated. Then, the kinetics parameters of equations were regressed by experiment data of different pressure and monomers composition; at last, CO/C₂H₄ copolymerization kinetic model was accomplished.In the kinetic model, calculated values were consistent with experimental data, in other word, the model was fit for the kinetical description of CO/C₂H₄ copolymerization in methanol.Base on the structure analysis of polyketone and dynamics research, a mechanism of chain growing for CO/C₂H₄ copolymerization using palladium catalyst in methanol is gained, which is composed of two circulations, the main circulation is CO/C₂H₄ insert into growing chain alternately, the hypo- circulation is C₂H₄ insert into growing chain continuously.更多还原