A novel process was developed for preferential conversion of lignin, a major constituent of biomass, into (C6 - C9)aryl methyl ethers, possessing very high octane numbers. In the procedure, lignin was subjected to (A) mild base-catalyzed depolymerization (BCD) with preservation of most of the lignin oxygen, followed by (B) mild, selective C - C hydrocracking, to complete the depolymerization to monocyclic phenols, and (C) subsequent etherification of the latter with methanol. Systematic studies were performed on the base-catalyzed depolymerization (BCD) and subsequent hydroprocessing stage as a function of processing variables, e.g., temperature, time, pressure, catalyst type and concentration, feed/solvent ratio, etc. The following main results were obtained: (a) low BCD temperatures in the range of 230 - 260 ºC result in the production of alkylated phenols and methoxyphenols, accompanied by oligomers of the latter (b) short BCD reaction times in the range of 2-5 min is sufficient for achieving high BCD yield, indicating that the reaction is very fast; (c) NaOH is a superior catalyst (as compared with other bases) and is highly suitable for use in the BCD stage; (d) low catalyst concentration in the range of 2.0 to 7.5 wt% is sufficient for achieving high BCD conversions; (e) presence of water (as high as 150 wt% relative to the lignin feed) in the BCD stage does not significantly reduce the lignin conversion, whereas it reduces the extent of undesirable ring methylation; (f) the removal (complete depolymerization) of oligomers in the subsequent selective C-C hydrocracking (HT) step can be accomplished by the use of solid superacid catalysts, e.g., Pt/SO42-/ZrO2 and Pt/WO42-/ZrO2; (g) superacids e.g., SO42-/MnOx/Al2O3, SO42-/MoOx/Al2O3, and SO42-/WOx/Al2O3, are suitable catalysts for etherification (ETR) of the phenolic BCD-HT product mixture with methanol, ultimately yielding a mixture of substituted aryl methyl ethers (mostly phenyl-, tolyl-, and dimethylphenyl methyl ethers) as main products, along with some C6-C9 multibranched paraffins. Such aryl methyl ethers boil within the gasoline range (160 - 200 ºC) and have very high octane numbers (142-166). Aryl methyl ethers are characterized by very low solubility in water and, therefore, could offer a major advantage in comparison with dialkylethers, e.g., MTBE, in regard to underground water contamination.
Paper 318b: Polymer-Based Aqueous Biphasic Systems as Improvement for Kraft Hardwood Pulping Process
In recent years, there has been increasing interest in trying to find alternatives to the Kraft pulping system that will yield pulp with Kraft-like strength properties, without the environmental drawbacks. Organosolv processes, a process using organic solvents to aid in the removal of lignin from wood, have been demonstrated to be highly efficient processes for the delignification of raw paper pulp. It was the results of the organosolv experience that inspired us to examine the effectiveness of polymer-based aqueous biphasic systems (ABS) applied to the delignification of cellulose in the paper pulping process. ABS are formed when certain water soluble polymers are combined with phase forming salts at critical concentrations. The utilization of ABS for novel separation has been the subject of many publications.
ABS represent wholly aqueous system that are safe, non-toxic, non-flammable, and relatively environmentally benign as an extraction media. We studied the detailed phase diagrams and partitioning data currently used in wholly aqueous solvent extraction or reactive extraction processes that may be applicable to the delignification of cellulosic materials at elevated temperature. It indicates that increaseing the concentration of salt improves the degree of phase divergence, as measured by tie line length for these biphasic systems. The results of different lignin species in PEG/salt ABS show that lignin prefers the polymer-rich phase of ABS. Four complete time-at-temperature (130-160 oC) batch-cooking experiments were made using a Kraft pulping solution with and without PEG. The results of wood chips composed of a mixture of Southern hardwood indicate that the use of PEG results in a pulp of lower Kappa Number, lower lignin content and higher residual pulp.
Paper 318c: Black Liquor Gasification in a Pressurized
Entrained-Flow Reactor: The Impact of Gasification Pressure on
Carbon-Containing Gases and Fixed Carbon Yields
The black liquor fed to the PEFR was a dried softwood kraft liquor of typical composition, with a nominal particle size of about 100 microns. The gasification atmosphere consisted of CO2 and/or water vapor in nitrogen. Particles entering the reaction zone of the PEFR were heated rapidly to the reaction temperature (1000oC), and and remained in the reactor for 0.3 – 5 seconds. The gases and particles were then collected in a water-cooled collector to quench the reaction. The particles were separated from the gases in a cyclone and filter for further analysis. The gases were analyzed for carbon species using a Fourier-Transform infrared spectrometer (FT-IR). In some runs, gas samples were removed through side ports in the reactor by a molecular beam device and analyzed by on-line mass spectrometry.
Each run was made by 1. bringing the reactor to temperature, 2. adjusting the primary, secondary, quench, and purge gas flow rates and compositions to the desired values (see Table 2), 3. charging the solids feeder with a known weight of black liquor solids, 4. setting the solids feeder to feed at the desired feed rate, 5. analyzing on-line for C-, H-, O-, and S-containing species in the product gas by FT-IR, and 6. running until the entire batch of black liquor solids had been fed
At the end of each run, the particles collected on the filter downstream of the quench/collector were removed and weighed to determine the char residue yield. These particles were stored for further chemical analysis. Some of these samples were sent for analysis of carbon, sodium, and chloride content.
Paper 318d: Treatment of Pulp Mill Liquors using Molten Alkaline Salt
An analysis will be presented of the potential for using molten alkaline salt thermal treatment of organic and salt aqueous residues from mill plant water reclamation schemes that concentrate these materials as a result of distillation or other means. Molten alkaline salt thermal processing is a relatively unique and not widely known unit operation. It utilizes a molten sparged bed of salts to efficiently conduct high temperature chemical reactions, including the oxidation of organics, neutralization of acid gas components, reduction of sulfur compounds to sulfides, and the conversion of various sodium salt species to caustic.
Molten alkaline salt has been well characterized in terms of environmental effluents and has been shown to have a maximum capability of destruction of organics with a minimum potential for emissions of dioxin or other toxins. It can be used to process highly chlorinated concentrates as well as alkaline concentrates. It is not an incineration process in any legal context.
The history of development of molten alkaline salt processing will be briefly presented. This includes demonstration units of a size and capacity suitable for the commercial treatment of paper and pulp mill concentrates. Recommended process flow sheets for using this technology will be presented as well as estimates of capital and operating costs. Separation of non-process chemicals and reclaiming plant chemicals for recycle will be discussed.
Paper 318e: Catalytic Upgrading of Succinic Acid and its Derivatives
Fermentation based technologies for succinic acid production from biomass-derived carbohydrates are now approaching commercial status, with succinate costs projected to be as low as $0.25/lb. Succinic acid has long been known to undergo a variety of reactions to useful commodity and specialty chemicals, but only with the forthcoming availability of inexpensive succinates do these pathways have commercial potential. Our research focuses on heterogeneous catalysis to facilitate selective, environmentally benign conversion of succinic acid and its derivatives to commodity and specialty products.
A novel catalytic process to produce itaconic acid via condensation of succinic acid or its derivatives with formaldehyde is described. Itaconic acid is a valuable monomer in the formulation of polymers because of its unique chemical properties, which derive primarily from the conjugation of its two-carboxyl groups and its methylene group. Vapor phase succinate conversion to form citraconic acid has been performed using a fixed bed reactor. A series of catalysts and support materials have been evaluated to achieve optimal yield of citraconic anhydride from succinates and formaldehyde. The effect of different catalyst characteristics (surface area and acid/base properties) on the yield of citraconic anhydride has been thoroughly investigated. Several different forms of succinates and formaldehyde have been employed. Optimization of reaction parameters over the preferred catalyst has been conducted and high yield and selectivity to citraconic acid have been achieved. The subsequent process steps for recovery of citraconic acid and isomerization of citraconic acid to itaconic acid have also been established. The process described here is anticipated to have significant economic advantages over the current fungal fermentation route.
Paper 318f: Gasification of Organic Materials from Water-Gas
Reaction
We are studying the formation of gases from organic materials, for exemple, glucose or some high polymer materials, using the high pressure and high temperture water whose condition is, for example, 600 degree and 10 MPa. Some experiments were carried out at the condition of SCW that is Super Critical Water. So we are going to present our results, about the conditions of water which enable the formation of herogen, methan and some other gases from organic materials. The effect of catalyst will be also showed.
Paper 318g: Effect of Borate on Boiling Point Rise of Black Liquor
This paper presents a study on the effect of borate addition on black liquor properties. The results from this study show that borate forms a complex with the black liquor. This complex reduces the effect of the borate salts on the black liquor's boiling point rise and reduces the viscosity changes.
Recently, there has been considerable interest in the use of borate-based autocausticizing to supplement or eliminate the calcining/causticizing cycle. On-going mill trials have produced promising results and indicate that this may be economical feasible alternative to the conventional calcining/causticizing cycle. A common situation is where 5 to 25% additional calcining/causticizing capacity is required. This requirement can be met by the additional of sodium borate to the liquor cycle.
An important question with the addition of borate to the liquor cycle is the effect on boiling point rise and the liquor's rheological properties. In this study different levels of sodium meta-borate (the borate salt that would be present in the black liquor) were added to commercial black liquor and the boiling point rise and viscosity of the resulting liquor measured. The boiling point rise of the liquor was measured over a wide temperature and pressure range and compared to the boiling point rise of non-borated black liquor and liquor with calcium carbonate added. These experiments show that the initial effect of borate at low levels of addition is similar to that of calcium carbonate. The boiling point rise of liquor initially increases with the addition of the borate as predicted for the addition of an inorganic salt. However, once the borate complexes with the black liquor, the boiling point rise decreases and is less than that observed with the addition of calcium carbonate. It was also found that while calcium carbonate quickly reaches its solubility limit and precipitates, the meta-borate is soluble in black liquor up to that required for complete autocausticizing. Work on the effect of borate on the viscosity of the black liquor is on going but the initial results indicate that the borate complex reduces the effect of the addition of the borate.
The results of these experiments are encouraging in that the boiling point rise due to the addition of the borate is less than that expected from the simple addition of inorganic salts. These behavior is explained by a complex between the borate and black liquor and is consistent with the recently observed boiling point rise in on-going mill trials. This makes borate-based autocausticizing more likely to be economically feasible.
