Study On Catalyst Optimization In The Process Of Dimerization Of Acetylene

Nieuwland catalyst (CuCl-NH4Cl-HCl-H2O) is an effective catalyst for acetylenedimeration, still used today. However, this method also has some disadvantages, such aslow productivity and selectivity of MVA, many by-products, which are easyaccumulation in the bottom of reactor and blocking reaction tube. Therefore, it isimportant for us to refine and improve the Nieuwland catalysts system through findingmore suitable catalyst additives. It studied that the effect of Nieuwland catalyst to thisrection, improved by1-butyl-3-methyl imidazolium chloride ([bmim]Cl), rare earthmetal salts, grapheme and stirring.Firstly, it explored the effects of rare earth metal salts, LaCl3and CeCl3forimproving Nieuwland catalysts. As a result, the former could get MVA mass yield10.66%, but the latter was5.87%which was less than black experiment. Afer adding upto [bmim]Cl in both of the two systems, ionic liquid had no effect to Nieuwland systemwith LaCl3, but was effective to CeCl3system. What’s worse, ionic liquid, because ofspecicial viscosity and polar sake, could promote the yield of DVA, which wasimportant to impact the selectivity of MVA. Density function theory simulations usedthe lowest energy theory to get a stable structure. It obtained that LaCl3with [bmim]Clformed a new ionic liquid ([bmim][LaCl4]), which can effectively reduce the activationof Cu+to acetylene and improved the results. Ce3+could change valence state, beunstable under acidic conditions, to bring negative impacts to this reaction.Then it further explored the effect of stirring to acetylene dimer, found that massyield of MVA increased to9.04%, compared to7.08%in black reaction, especially thehigh selectivity of MVA98.47%. What’s more, yield and selectivity of MVA was32.84%, DVA yield was0.074%in Nieuwland catalysts with [bmim]Cl. It has the sameeffects in the systems with LaCl3and CeCl3, it can improve the yield and selectivity ofMVA and reduce the yield of DVA. Therefore, strirring can obviously improve theexperiment results.It explored the effect of different amount grapheme to acetylene dimer, got the bestresults at2.5mg grapheme. Then it researched the improvement of the effective raremetal LaCl3and [bmim]Cl. UV and FT-IR was used to analyzed the role of grapheme.In the end, it studied that the effect of different quantity grapheme oxide toacetylene dimer, got that MVA reduced as the grapheme oxide increased because ofincreasement of pH. At the same time, MVA increased abosolutely as DVA yield reduced to zero seriously. We found that carboxyl in the grapheme oxide could loseprotons easily through infrared spectra.