Study On Synthesis Of N,N-dimethyl Amine Polyethylene Glycol Ether And Decarbonization Property

Synthesis of N,N-dimethyl amine polyethylene glycol ether was divided into two steps.The first step is to form multi-glycol chain with terminal amino by N,N-dimethyl ethanolamine(DMEA) and ethylene oxide (EO), in the the autoclave, generating N,N-dimethyl polyethyleneglycol amine (DMPEA); the second step is the termination process of terminal hydroxy byWilliamson etherification reaction of DMPEA and CH3Cl, the terminal hydroxyl groupsbecoming alkoxy groups. After the post-treatment and purification of the crude product,complete the characterization and the relevant property measurement, and make the preliminaryapplication for the final synthesized products. In this paper, the focus and innovation is tosynthesize new substance and then complex it with polyethylene glycol dimethyl ether (NHD)to form complex-type desulfurization and decarbonization solvent, having good developmentprospects and value.The ring-opening addition reaction, with DMEA) and EO as raw materials, was occurredunder alkaline (NaOH) conditions, generating DMPEA. Through single factor experiments, theoptimal conditions of process were established. That is n (DMEA)∶n (EO)=1∶3, the amountof alkali catalyst was0.2%(percentage of the total mass of raw materials), the reactiontemperature was110℃, the reaction time was3.5h. Three repetitive experiments were carriedout under the optimum conditions, and the three experimental results were stable andreasonable, the average conversion rate of DMEA reaching90.3%, mainly getting multi-glycolchain with1to5ethoxy groups. Make the quantitative analysis by gas chromatography andmake the qualitative analysis of functional groups by infrared spectroscopy.In order to obtain the organic amine ethers with the stable structure and properties, theautoclave synthesis products DMPEA were capped by the terminal hydroxyl group togenerating N,N-dimethyl amine polyethylene glycol ether (DMPEAE). The terminal hydroxylgroups were converted to alkoxy groups by Williamson etherification method with DMPEA asthe raw material, sodium hydroxide as the alkoxide reagent and chlorine methane gas asetherification agent. Through single factor and orthogonal experiments, the optimum conditionsof etherification were established: solid-liquid ratio of raw materials n (NaOH)∶ n (DMPEA)=1.3∶1, the amount of phase transfer catalyst (PTC/TBAB) was0.2%(percentage of themass of solid and liquid raw materials), the reaction temperature was70℃, the stirring speedwas400r/min and the etherification time was5h. And the order of four single factors about theeffect on the etherification reaction was identified, followed by stirring speed, etherificationtime, the solid-liquid ratio of raw materials and the reaction temperature. Three repetitiveexperiments were carried out under the optimum conditions, and the three results werereasonably and stable, with the average degree of etherification getting to98.2%. The establishment of degree of etherification was based on the hydroxyl value before and after theetherification reaction. After the refining processing of the etherification products, make theanalysis and characterization for the target products by infrared spectroscopy and GC-MS.A certain purity of the single-component product dimethylamino monoethoxylate ether(N1’), dimethylamino diethoxylate ether (N2’) and dimethylamino triethoxylate ether (N3’) wereobtained by distillation the etherification products under reduced pressure conditions. N1’、N2’、N3’ and dimethylamino polyethoxylate ether (Nmix’) were used as absorbing solutions to grabacid gas carbon dioxide to research their decarbonization application. The results showed thatthe low temperature was benefical to gas absorption, while high temperature was benefical todesorption. Therefore gas absorption at low temperature was preferably effective. Besides, indecarbonization capacity, N1’ and Nmix’ were generally higher than N2’ and N3’. In addition,organic amine ethers mixed with polyethylene glycol dimetyl ether (NHD) were used ascomplex-type absorption solution to be researched. The results illustrated that the absorptioncapacity was gradually increased along with an increase of proportion of organic amine ethers.In detail, when the proportion of N1’ or Nmix’ in the compound solution got to30%, theabsorption solution showed the better absorption capacity than NHD, while the ratio of N2’ andN3’ must reach40%. The preliminary application of such terminal tertiary aminopolyoxyethylene ether as N1’、N2’、N3’ and Nmix’ and complex-type absorption solvent indesulfurization and decarbonization developed a new a new idea in acid gas purification, bothto improve the performance of acid gas purification application and cost savings, having animportant role in the field of acid gas purification.