合成甲醇中杂质乙醇成因及含量的测定

引言 2005年3月和2006年4月。笔者先后两次参观考查了四座生产甲醇的厂家，二个甲醇使用单位和省级分析检测中心，主要考查课题为合成甲醇工艺中的杂质乙醇成因及含量的测定。其中主要对四个厂的造气工艺、气体成份，合成塔的温度、压力、催化剂、精馏塔、粗甲醇和精甲醇的试验方法和检验规则进行了考查研究分析。考查结果为合成气中的碳氢化合物含量是影响合成甲醇时杂质乙醇成因及含量成因的主要依据。本文把考查的过程和结果分析介绍如下。     

对GB 26373《乙醇消毒剂卫生标准》中乙醇测定方法的改进

本文采用PEG-20M毛细管柱,氢火焰离子化检测器对乙醇消毒剂中的乙醇及常见杂质甲醇进行气相色谱分析。当N_2压力为0.06MPa,柱温为65℃时,甲醇和乙醇的柱效较高,分离效果较好,分析过程快速。以正丙醇作内标,f_(甲醇)=1.813、f_(乙醇)=1.287,RSD3.2%;甲醇的加标回收率约为105%,乙醇的加标回收率接近100%。本方法作为对GB 26373《乙醇消毒剂卫生标准》中乙醇测定方法的改进,可以用于快速定量分析乙醇消毒剂中的乙醇含量以及杂质甲醇的含量。     

甲醇产品中乙醇含量指标探讨

1问题的提出 工业生产甲醇产品中的杂质含量,按照国标规定(乙醇除外),合格品＜0.02%,优级品＜0.01%.工业甲醇中的乙醇含量一般为0.01%～0.02%,由于甲醇的下游产品对该项指标要求并不严格,故国标中未作规定.凡是以铜催化剂制得的粗甲醇,不论其原料结构和合成条件如何,通过两塔或三塔蒸馏,只要设计合理、安装正确、操作正常,绝大部分的产品质量可达到优级品标准,可满足甲醇下游产品对甲醇质量的要求.     

甲醇合成催化剂使用寿命中后期保证甲醇产品质量的优化措施

陕西兴化集团有限责任公司300 kt/a甲醇装置开车以来,甲醇产品符合GB 338—2004中优等品质量要求,但随着甲醇合成催化剂使用时间的延长,尤其是催化剂进入使用寿命中后期,粗甲醇中杂质(以乙醇标定)含量明显上升,导致精甲醇产品出现高锰酸钾值超标、水溶性不合格等问题,而随着陕西兴化甲胺装置、乙醇装置的先后建成投产,对甲醇产品质量提出了更加严格的要求。经分析与探索,通过从甲醇合成和甲醇精馏两方面采取相应的工艺优化措施,有效保证了精甲醇产品质量的稳定,为下游甲胺、乙醇产品的生产提供了良好的原料保障,提升了企业产品的竞争力。     

甲醇合成影响因素与粗甲醇中乙醇含量超标研究

操作条件、入塔气组成以及催化剂性能是影响甲醇合成反应的主要因素。文章对甲醇合成反应的影响因素进行分析,找出甲醇装置开车初期粗甲醇中乙醇含量超标的具体原因,并在此基础上进行优化操作,粗甲醇中乙醇含量达到或优于设计指标。     

内标法测定甲醇中乙醇含量及注意事项

应用内标法对我公司生产的甲醇中乙醇含量进行分析,使用气相色谱法,在选定的条件下,使甲醇中的乙醇等杂质得到分离。使用火焰离子化检测器进行检测,测定定量校正因子,根据计算准确得出乙醇的质量分数。满足我厂对出厂产品指标的检测要求。     

气相色谱分析法在甲醇生产中的作用分析

气相色谱分析法能够精确测定工艺参数、操作稳定,在精甲醇生产中有着非常广泛的应用。本文介绍了以粗甲醇中甲醇、水、乙醇及杂质的测定和精甲醇中杂质的测定为例介绍了气相色谱分析法在精甲醇生产中的作用。     

甲醇中乙醇含量对高品质醋酸产品成本的影响

针对甲醇低压羰基合成乙酸生产工艺中,原料甲醇掺杂的少量乙醇与一氧化碳羰基化反应生成丙酸,造成醋酸产品质量降低的问题展开分析.介绍了丙酸生成机理,以及丙酸含量对乙酸产品质量的实际影响.通过对降低甲醇中乙醇含量,以及降低乙酸中的丙酸含量的生产成本进行对比核算,分析了原料甲醇中乙醇含量的高低对醋酸产品成本的实际影响.结果表明...     

3+1塔甲醇精馏优化操作降低产品中乙醇含量

结合我公司一期30万吨/年甲醇装置4塔甲醇精馏的工艺流程特点和生产实际,根据乙醇的生成机理和原因分析,在甲醇合成和精馏过程中,经过一系列技改和工艺优化操作,将产品精甲醇中的乙醇含量降低至10mg/m3以下。     

联醇技术流程模拟优化分析探讨

对甲醇合成工艺进行了评述,提出联醇法甲醇合成工艺重要意义。采用管壳式合成塔,使用C207型甲醇合成催化剂,建立联醇法甲醇合成工艺系统模型,借助化工稳态模拟软件,对甲醇合成流程进行了全流程模拟,得到该流程的基本工艺数据。利用化工稳态软件中的灵敏度分析工具从循环量变化、原料气组成、原料气中的甲醇含量等方面论述了操作条件变化对甲醇合成的影响,并进行优化研究。     

Continuous synthesis process of methanol at low temperature from syngas using alcohol promoters

A continuous process for low-temperature methanol synthesis from CO/CO₂/H₂ based on the promoting effect of alcohol solvent has been developed. 2-butanol, acting as a promoter, with the aid of Cu/ZnO solid catalyst, realized the high efficient synthesis of methanol with one-pass methanol yield of 47.0% and methanol selectivity of 98.9% at temperature as low as 443 K and 50 bar, which can be a very promising method for methanol production at low temperature.     

管壳式甲醇合成装置增产节能改造技术

针对管壳式甲醇合成塔不易大型化、催化剂装填率低、催化剂更换周期短等缺点,对甲醇合成塔进行了改造,结果表明,增加了单塔的生产能力,提高了催化剂的更换周期;对合成装置中的甲醇分离器进行了改造,提高了甲醇的分离效率,降低了循环气中的甲醇含量,从而提高了CO的单程转化率,提高了醇净值;通过对甲醇合成塔和甲醇分离器的改造,整体单系列生产能力比原装置生产能力提高了10%以上,有效地降低了生产成本,而不影响装置的安全性和操作稳定性。     

The promoting effect of alcohols in a new process of low-temperature synthesis of methanol from CO/CO2/H2

The catalytic promoting effects of eleven different alcohols, as reaction medium, on the synthesis of methanol from feed gas of CO/CO₂/H₂ on Cu/ZnO solid catalyst were investigated. Added alcohol altered the reaction route to realize a low-temperature synthesis method where formate was an intermediate. Many alcohols showed catalytic promoting effect for methanol formation at temperature as low as 443 K, remarkably lower than that in the present industrial ICI process.     

A new low-temperature methanol synthesis method: Mechanistic and kinetics study of catalytic process

Mechanism and kinetics of catalytic process for a new low-temperature methanol synthesis on Cu/ZnO catalysts from syngas (CO/CO₂/H₂) using catalytically active alcohol promoters were investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Two intermediate species, adsorbed formate species and alkyl formate species, were formed in this synthesis process. The adsorbed formate species easily reacted with ethanol or 2-propanol at 443 K and atmospheric pressure, and the reaction rate with 2-propanol was faster than that with ethanol. Alkyl formate was readily reduced to form methanol at 443 K and 1.0 MPa, and the hydrogenation rate of 2-propyl formate was found to be quicker than that of ethyl formate. As a promoter, 2-propanol exhibited a higher activity than ethanol in the reaction of the low-temperature methanol synthesis.     

Lipase-Mediated Synthesis of Fatty Acid Esters Using a Blending Alcohol Consisting of Methanol and 1-Butanol

Lipase-mediated transesterification of soybean oil with a blending alcohol consisting of methanol and 1-butanol for synthesis of fatty acid esters was carried out. Lipase from Thermomyces lanuginosa (Lipozyme TL IM) was used as a biocatalyst. The lipase was purchased from Novozymes (Seoul, Republic of Korea). The effects of the molar proportions of methanol and 1-butanol in the blending alcohol, reaction temperature, enzyme loading and water content were investigated, for reaction optimization. The relative consuming rates of methanol and 1-butanol during the reaction were also explored. Among seven different ratios of alcohol blends employed in this study, that containing 80 mol% methanol gave the highest yield of fatty acid esters. Optimum reaction temperature, enzyme loading, and water content were 30 °C, 15% (based on the substrate weight), and 0.3% (based on the substrate weight), respectively. Water influenced significantly the reaction rate and yield. On the transesterification, the degree of reaction of methanol was higher than that of 1-butanol and the presence of 1-butanol contributed to increase of the reaction rate as well as yield. The maximum yield of ca. 98 wt% was achieved under the optimized condition.     

Spectroscopic and Kinetic Analysis of a New Low-Temperature Methanol Synthesis Reaction

The spectroscopy and kinetics of a new low-temperature methanol synthesis method were studied by using in situ DRIFTS on Cu/ZnO catalysts from syngas (CO/CO₂/H₂) using alcohol promoters. The adsorbed formate species easily reacted with ethanol or 2-propanol at 443 K and atmospheric pressure, and the reaction rate with 2-propanol was faster than that with ethanol. Alkyl formate was easily reduced to form methanol at 443 K and 1.0 MPa, and the hydrogenation rate of 2-propyl formate was found to be faster than that of ethyl formate. 2-Propanol used as promoter exhibited a higher activity than ethanol in the reaction of the low-temperature methanol synthesis.     

Preparation of bifunctonal catallysts

Catalyzed reactions are usually a combination of various reaction pathways that require Catalysts to possess more than one chemical function. These reaction types and Catalyst functions are reviewed and bifunctionality of Catalysts is exemplified in the ensemble control effect for oxidation of carbons to CO/CO₂, double redox oxide Catalysts for partial oxidation of methane, base-hydrogenation Catalysts for methanol and higher alcohol synthesis as well as the water gas shift reaction, hydrogenation-CO insertion Catalysts for higher alcohol synthesis, and acid- hydrogenation Catalysts for the synthesis of ethers.     

Growth process and short chain alcohol separation performance of fluoride-containing NaY zeolite membrane

Growth process of the NaY zeolite membranes was investigated by fluoride-containing precursor synthesis gel.Compared with the fluoride-free precursor synthesis gel,the irregular NaY zeolite crystals were dissolved into amorphous by the fluoride-containing precursor synthesis gel initially,the amorphous contained the Y-type zeolite characteristic bands by the IR characterization.The fine square NaY zeolite crystals arose from the amorphous,which were accumulated and gradually grew into a dense NaY zeolite layer on the support surface after 6.5 h.Because the excessive NaY zeolites were dissolved by the strong alkaline and fluoride-containing precursor synthesis gel,there was plenty of amorphous on NaY zeolites layer for prolonging the crystallization time.The assynthesized NaY zeolite membranes had a good separation performance and repeatability for separation of 10 wt%methanol(MeOH)/methyl methacrylate(MMA) mixture by pervaporation,the flux and separation factor were(1.27 ± 0.07) kg·M~(-2)·h~(-1) and(4900 ± 1500) at 323 K,respectively.Besides,the NaY zeolite membranes were applied to separate the other short chain alcohol from the various alcohol/organic ester and alcohol/organic ether mixtures,the NaY zeolite membranes showed high short chain alcohol perm-selectivity.     

甲醇供需失衡局面仍将持续

甲醇作为重要的化学工业基础原料和清洁液体燃料,被广泛应用于有机合成、医药、农药、涂料、染料等领域,主要用来生产甲醛、醋酸、MTBE、对苯二甲酸二甲酯、丙烯酸甲酯等产品以及醇醚燃料。随着甲醇制烯烃和甲醇燃料等新兴领域的不断开发,虽然为甲醇行业开拓了更为广阔的应用前景,但由于我国甲醇产能无序过快增长、大量进口产品的冲击、下游需求疲软以及投资新建装置热度不减等因素的影响,造成我国甲醇严重供过于求,我国甲醇供需失衡的局面仍将持续。     

Production of biodiesel from waste fryer grease using mixed methanol/ethanol system

Transesterification of waste fryer grease (WFG) containing 5–6 wt.% free fatty acid (FFA) was carried out with methanol, ethanol, and mixtures of methanol/ethanol maintaining the oil to alcohol molar ratio of 1:6, and initially with KOH as a catalyst. Mixtures of methanol and ethanol were used for transesterification in order to use the better solvent property of ethanol and rapid equilibrium using methanol. Formation of soap by reaction of FFA present in WFG with KOH instigated difficulty in the separation of glycerol from biodiesel ester. To untangle this problem, two-stage (acid and alkali catalyzed) method was used for biodiesel synthesis. More than 90% ester was obtained when two-stage method was used compared to ∼ 50% ester in single stage alkaline catalyst. In the case of mixed alcohol, a relatively smaller amount of ethyl esters was formed along with methyl esters. Acid value, viscosity, and cetane number of all the esters prepared from WFG were within the range of the ASTM standard. Esters obtained from WFG showed good performance as a lubricity additive.