Application of microwaves on the production of liquid biofuels

《2008年气候变化法》设定了到2050年将英国温室气体排放量(GHG)减少80%的挑战性目标。公路运输、航空和航运排放了英国约33%的温室气体排放，该部门消耗了约38%的最终能源消耗。英国政府已经认识到使用生物燃料的关键作用，生物燃料是从生物质和废物等可再生资源中提取的燃料，以减少运输和确保能源安全。快速热解正在巩固，作为将不可食用的生物质转化为可用作生物燃料前体的液体(生物油)的途径。生物油的含氧量比原油高得多(前者含氧量为10-40wt.%，而后者含氧量为1wt.%)。由于这种含氧量，它与石油衍生燃料和基础设施(管道、加工装置、发动机……)不兼容。当前使用的。因此，生物油在应用于现有系统之前，需要升级阶段来去除氧气。增加升级阶段使生物质转化为液体的过程更加复杂，并导致更高的资本和运营成本。现在需要技术突破，才能获得清洁和负担得起的生物燃料。该项目提出了一种新的方法：使用微波加热从生物质中生产生物燃料的更简单、更有效的过程。应用于化学反应的微波已经显示出类似于任何人在家用微波炉或炉子上加热一杯牛奶时都能观察到的优势。微波炉更快、更干净。另外，针对生物质微波热解的特殊应用，还生产了含氧量较低的生物油。但目前还没有系统的研究表明微波热解的优势。因此，在这个项目中，我们的目标是了解温度或反应时间的变化如何影响所产生的生物油的数量及其组成(氧含量)。我们还在测试这样一个假设，即微波可以帮助催化升级过程，与传统升级相比，提高生产的生物燃料的数量和质量。在生物油的微波升级方面几乎没有做过任何工作。但基于微波裂解的结果和一些石油馏分的微波改质研究，预期会有良好的结果；这些研究表明，与传统工艺相比，可以生产更好的油。这一假设将通过一系列实验室实验进行验证。如果能够证明微波可以在与传统工艺相似(或更好)的操作条件下生产含氧量更低的升级生物油，那么这是一个更有效的过程，当它扩大规模时，可能会更经济和可持续。发展微波辅助的生物质转化为液体的过程作为一种经济和可持续的生物燃料生产途径，将有利于生物燃料进入英国运输部门的渗透率和成本。微波可以与其他可再生能源技术相结合，对清洁技术的发展产生影响。微波是由电力产生的。如果使用微波发电所需的电力来自风能和太阳能等可再生能源，则可以避免温室气体排放。此外，微波加热的适用性是巨大的，可以扩展到生物质转化之外；它可以用于从制药过程到塑料生产的多个部门。总体而言，在该项目期间收集的知识将影响应用于工业流程的微波的发展，并将有助于英国工业部门在中长期内将自己定位为使用这项技术的世界领先者。

The Climate Change Act 2008 set the challenging goal of reducing the UK greenhouse gas emissions (GHG) by 80% by 2050. The road transport, aviation, and shipping emit approximately 33% of UK greenhouse emissions, and the sector consumes around 38% of the total final energy consumption. The UK Government has acknowledged the key role of the use of biofuels, fuels made from renewable sources such as biomass and waste, in order to decarbonise transportation and ensure energy security.Fast pyrolysis is consolidating as route for conversion of non-edible biomass into liquids (bio-oil) that can be used as biofuel precursors. The bio-oil presents a much higher content in oxygen than the crude oil (10-40 wt.% of oxygen in the former compared to < 1 wt.% of O in the latter). And because of this oxygen content, it is not compatible with the petroleum-derived fuels and infrastructure (pipelines, processing units, engines...) currently used. Therefore, the bio-oil requires upgrading stages to remove the oxygen before being applicable in the existing systems. The addition of the upgrading stages makes the biomass-to-liquid process more complex and incurs in higher capital and operating costs. Technological breakthroughs are now required for clean and affordable biofuels to become available. This project sets out a new approach: using microwaves to heat simpler and more efficient processes for the production of biofuels from biomass. Microwaves applied to chemical reactions have shown similar advantages to those that anybody can observe when heating a glass of milk in the household microwave or on the stove. The microwave oven is faster and cleaner. In addition, for the particular application of microwave pyrolysis of biomass, bio-oil with lower oxygen content has been produced. But there is not systematic study which shows the advantages of using microwave pyrolysis. So in this project we aim to understand how changes in temperature or reaction time have an influence on the amount of the produced bio-oil and its composition (oxygen content). We are also testing the hypothesis that microwaves can aid the catalytic upgrading process to enhance the quantity and quality of the produced biofuel compared to conventional upgrading. There is virtually no work done on the microwave upgrading of bio-oil. But good results are expected based on the results from microwave pyrolysis and some studies on microwave upgrading of petroleum fractions; those have shown that better oil is produced compared to conventional processes. The hypothesis will be tested through a programme of laboratory experiments. If microwaves can be demonstrated to produce an upgraded bio-oil with lower oxygen content at similar (or better) operating conditions than conventional processes then it is a more efficient process and, when scaling it up, will potentially be more economic and sustainable.Developing the microwave-assisted biomass-to-liquid process as an economic and sustainable route for biofuel production will benefit the penetration and cost of biofuels into the UK transport sector. Microwaves can have an impact in the development of clean technologies as it can be coupled with other renewable energy technologies. Microwaves are generated from electricity. GHG emissions can be avoided when using microwaves if the electricity required for their generation is produced from renewable energy sources such as wind and solar power. Moreover, the applicability of microwave heating is huge and extendable beyond the biomass conversion; it can be used in multiple sectors, from pharmaceutical processes to production of plastics. Overall, the knowledge gathered during this project will impact the development of microwaves applied to industrial processes and will help the UK industrial sector to position itself as world leaders in the use of this technology in the mid- and long-term.