GOALI: Low-Ash Lignin Biofuel from Black-Liquor Streams

PI：Thies，MarkProposal编号：1236759机构：克莱姆森大学标题：GALI：低灰分黑液木质素生物燃料木质素是地球上最常见的有机化合物之一，约占所有有机碳的30%，在干燥的基础上约占木材的30%。只有纤维素含量更丰富。如果木质素能够在干燥、低灰分(0.5%灰分)的状态下从制浆造纸厂的黑液副产流中分离出来，结果将是一种能量含量与煤炭基本相同的极好的生物燃料。最近，Clemson和LLC2的研究人员发现，通过在中等温度和压力下将黑液与气态二氧化碳接触，可以从硫酸盐厂黑液中以低粘度、易于处理的液体的形式沉淀木质素。此外，与初始黑液相比，这种液体木质素相降低了灰分含量，随后可以通过有机可再生酸酸化进一步降低灰分含量。基于这一发现，该团队设想了一种液体木质素低灰分净化(LLLAP)工艺，用于从纸浆和造纸厂的黑液流中回收清洁、低灰分(0.5%)的生物燃料木质素。如果美国100多家大型纸浆和造纸厂中有50家实施这一变化，每年将产生300万吨生物质燃料作为电力生产的煤炭替代品，从而每年减少1500万吨二氧化碳。从长远来看，如果所有纸浆和造纸厂都将所有黑液送到LLLAP工艺，美国电力生产的煤炭使用量将减少2%。该项目的目标如下：a.设计和建造LLLAP工艺的连续工艺、研究规模的装置，并用于研究LLLAP操作参数对木质素产品质量的几个测量指标的影响，包括产率、灰分纯度和低聚物组成。确定LLLAP操作条件对产品质量的影响将是困难的，除非人们能够更好地量化一般的硫酸盐黑液，特别是液体木质素的分子性质。因此，通过对LLLAP流程的改进，即通过连续递增的pH降低，将压缩的CO2降至~9，从而分离出窄馏分的液体木质素。然后，将表征这种木质素的本体和分子性质。例如，对于绝对质量和低聚物信息，将采用MALDI质谱仪。对液体木质素进行分级，以酸化、无盐的形式进行分子表征，在这种形式下，分子量和沉淀倾向等性质之间应该存在更好的关系。以前对其他齐聚体系的研究表明，多阶段超临界萃取和高温凝胶渗透层析具有良好的选择性，有时甚至可以分离出单个物种。通过MALDI质谱仪，根据低聚组分的组成对所得到的微级分进行表征。将计算结果与上述的结果进行比较。分离步骤，建立液体木质素切片的含盐量和低聚物组成之间的关系，以及它们对二氧化碳诱导沉淀的倾向，并利用这些结果对LLLAP进行改性，以获得低灰分产品。世界上已有20多家造纸和纸浆公司表示对LLLAP工艺和液体木质素技术感兴趣，因此，如果我们的低灰分目标真的能够实现，将会有大量的许可机会。最后，从外展的角度来看，研究小组将通过SC ETV广播节目Your Day向公众传播研究成果。

PI: Thies, MarkProposal Number: 1236759Institution: Clemson UniversityTitle: GOALI: Low-Ash Lignin Biofuel from Black-Liquor StreamsLignin is one of the most common organic compounds on earth, comprising about 30% of all organic carbon and about 30% of wood on a dry basis. Only cellulose is more abundant. If lignin could be isolated from the black-liquor by-product stream of a pulp and paper mill in a dry, low-ash ( 0.5% ash) state, the result would be an excellent biofuel with essentially the same energy content as coal. Recently, Clemson and LLC2 researchers have discovered that lignin can be precipitated from kraft mill black liquor in the form of a low-viscosity, easy-to-handle liquid phase by contacting the black liquor with gaseous CO2 at moderate temperatures and pressures. Furthermore, this liquid-lignin phase, which has reduced ash content vs. the starting black liquor, can subsequently be further reduced in ash content by acidification with organic, renewable acids. Based on this discovery, the team envisions a liquid-lignin low-ash purification (LLLAP) process for recovering a clean, low-ash ( 0.5%), biofuel lignin from the black-liquor stream of a pulp and paper mill. If 50 of the 100+ large pulp and paper mills in the United States implemented this change, 3 million tons of biomass fuel would be generated a year as a coal replacement for electric power production, enabling a reduction of 15 million tons of CO2/yr. If in the longer term all pulp and paper mills sent all of their black liquor to the LLLAP process, there would be a 2% reduction in the use of coal for U.S. electric power production. These are significant numbers.The objectives of the project are as follows:a. Design and construct a continuous-process, research-scale unit of the LLLAP process and use to investigate the effect of LLLAP operating parameters on several measurements of lignin product quality, including yield, ash purity, and oligomeric composition.b. Determining the effect of LLLAP operating conditions on product quality will be difficult unless one can better quantify the molecular nature of kraft black liquor in general and of liquid lignin in particular. Thus narrow fractions of liquid lignin will be isolated via a modification of the LLLAP process, that is, by successive incremental pH reduction with compressed CO2 down to a pH of ~9. Then the bulk and molecular properties of this lignin will be characterized. For example, for absolute mass and oligomer information, MALDI mass spectrometry will be employed.c. Fractionate the liquid lignin for molecular characterization in the acidified, salt-free form, where a more well-behaved relationship between properties such as molecular weight and propensity for precipitation should exist. Previous work with other oligomeric systems has demonstrated that multi-stage, supercritical extraction followed sequentially by high-temperature gel permeation chromatography gives excellent selectivities, and individual species can even sometimes be isolated. Characterize resulting micro-fractions in terms of their oligomeric composition via MALDI mass spectrometry. Use the results with those from the above ?pH? fractionation step to establish a relationship between the salt content and oligomeric composition of liquid lignin cuts, and their propensity for CO2-induced precipitation, and use these results to modify LLLAP so as to achieve a lower-ash product.More than 20 paper and pulp companies around the world have expressed interest in the LLLAP process and liquid lignin technology, so there will be significant licensing opportunities if our low-ash targets can indeed be achieved. Finally, from an outreach standpoint, the research team will disseminate results to the general public through the SC ETV Radio program Your Day.