Royal Institute of Technology-KTH, Department of Chemical Engineering and Technology, Chemical Technology, Teknikringen 42, SE-10044 Stockholm, Sweden.
J Chromatogr A. 2012 Jul 20;1247:134-45. doi: 10.1016/j.chroma.2012.05.060. Epub 2012 May 24.
An on-line gas chromatographic (GC) system has been developed for rapid and accurate product analysis in catalytic conversion of syngas (a mixture of H₂ and CO) to alcohols, so called "higher alcohol synthesis (HAS)". Conversion of syngas to higher alcohols is an interesting second step in the route of converting coal, natural gas and possibly biomass to liquid alcohol fuel and chemicals. The presented GC system and method are developed for analysis of the products formed from syngas using alkali promoted MoS₂ catalysts, however it is not limited to these types of catalysts. During higher alcohol synthesis not only the wanted short alcohols (∼C₂-C₅) are produced, but also a great number of other products in smaller or greater amounts, they are mainly short hydrocarbons (olefins, paraffins, branched, non-branched), aldehydes, esters and ketones as well as CO₂, H₂O. Trace amounts of sulfur-containing compounds can also be found in the product effluent when sulfur-containing catalysts are used and/or sulfur-containing syngas is feed. In the presented GC system, most of them can be separated and analyzed within 60 min without the use of cryogenic cooling. Previously, product analysis in "higher alcohol synthesis" has in most cases been carried out partly on-line and partly off-line, where the light gases (gases at room temp) are analyzed on-line and liquid products (liquid at room temp) are collected in a trap for later analysis off-line. This method suffers from many drawbacks compared to a complete on-line GC system. In this paper an on-line system using an Agilent 7890 gas chromatograph equipped with two flame ionization detectors (FID) and a thermal conductivity detector (TCD), together with an Agilent 6890 with sulfur chemiluminescence dual plasma detector (SCD) is presented. A two-dimensional GC system with Deans switch (heart-cut) and two capillary columns (HP-FFAP and HP-Al₂O₃) was used for analysis of the organic products on the FIDs. Light inorganic gases (H₂, CO, CO₂, N₂) and methane were separated on packed columns and quantified with the TCD. The "sulfur GC" was optimized for on-line trace level sulfur analysis in hydrocarbon matrices and used to understand to which degree sulfur is released from the catalyst and incorporated into the liquid product, and if so in which form. The method provides excellent quantitative measurements with a carbon material balance near 99.5% (carbon in/carbon out) for individual measurement points.
已开发出一种在线气相色谱 (GC) 系统，用于快速准确地分析合成气 (H₂ 和 CO 的混合物) 催化转化为醇的产物，即所谓的“高级醇合成 (HAS)”。将合成气转化为高级醇是将煤、天然气和可能的生物质转化为液体醇燃料和化学品的途径中的一个有趣的第二步。所提出的 GC 系统和方法是为使用碱促进的 MoS₂催化剂分析合成气产物而开发的，但不限于这些类型的催化剂。在高级醇合成过程中，不仅会生成所需的短链醇（∼C₂-C₅），还会生成大量其他产物，主要是短链烃（烯烃、烷烃、支链、非支链）、醛、酯和酮以及 CO₂、H₂O。当使用含硫催化剂和/或含硫合成气进料时，也可以在产物流出物中检测到痕量的含硫化合物。在所提出的 GC 系统中，大多数化合物可以在无需使用低温冷却的情况下在 60 分钟内分离和分析。在此之前，在“高级醇合成”中，产物分析大多是在线和离线部分进行的，其中轻气体（室温下的气体）在线分析，液体产物（室温下的液体）在阱中收集以供稍后离线分析。与完整的在线 GC 系统相比，这种方法存在许多缺点。本文介绍了一种使用配备有两个火焰离子化检测器 (FID) 和一个热导检测器 (TCD) 的安捷伦 7890 气相色谱仪以及配备有硫化学发光双等离子体检测器 (SCD) 的安捷伦 6890 在线系统。二维 GC 系统带有 Dean 开关（切分）和两根毛细管柱（HP-FFAP 和 HP-Al₂O₃），用于 FIDs 上的有机产物分析。轻无机气体（H₂、CO、CO₂、N₂）和甲烷在填充柱上分离，并使用 TCD 定量。“硫 GC”针对烃基质中的痕量硫在线分析进行了优化，并用于了解硫从催化剂中释放并掺入液体产物的程度，如果有，以何种形式掺入。该方法提供了极好的定量测量，单个测量点的碳物质平衡接近 99.5%（碳进/碳出）。
