Product Analysis from Direct Liquefaction of Several High-Moisture Biomass Feedstocks

Abstract

Experimental results are reported for high-pressure liquefaction of high-moisture biomass. The feedstocks included macrocystis kelp, water hyacinths, spent grain from a brewery, grain sorghum field residue and napier grass. The biomass was processed in a batch autoclave as a ten weight percent slurry in water with sodium carbonate catalyst and carbon monoxide gas. Thirty-minute experiments were performed at 350°C with operating pressures ranging from 270 to 340 atmospheres. The oil products were collected by methylene chloride and acetone extractions. Oil yields ranged from 19 to 35 mass percent on a moisture and ash-free basis. The oil products contained from 9.9 to 16.7 percent oxygen with hydrogen to carbon atomic ratios from 1.36 to 1.61. Significant nitrogen content was noted in the oil product from those feedstocks containing nitrogen (kelp, hyacinth, spent grain). Chemical composition analysis by gas chromatography/mass spectrometry demonstrated many similarities between these products and wood-derived oils. The nitrogen components were found to be mainly saturated heterocyclics.Significant progress has been made over the past fifteen years toward the development of processes for direct production of liquid fuels from biomass. Process research has generally progressed along two lines -flash pyrolysis and high-pressure processing. Extensive analysis of the liquid products from these two types of processes has demonstrated the significant process-related differences in product composition. However, the effect of feedstock has received a lesser degree of attention.

Preliminary Characterization of Raw Oil Products From the Thermochemical Conversion of Swine Manure

“…By difference, the oxygen content plus all the other traceable compounds in the TCC oils was calculated to be about 12% with a standard deviation of 5%. Experimental results showed that the water content in the raw TCC oils was affected less by the operating parameters, varying from 11.3% to 15.8%.Comparison of the above results to those of typical pyrolysis and liquefied oils is summarized in table 1.The elemental composition of TCC oils was very similar to that of liquefied oil obtained from kelp (Elliott et al, 1988). This means that both processes underwent a similar chemical mechanism except that the liquefied oil from kelp was obtained under much harsher operating conditions and the oil yield was much lower (about 20%) than that in the TCC process (62%-65%).…”

“…[c] Summarized from different pyrolysis and liquefaction processes (Rick and Vix, 1991). [d] Extracted from kelp liquefaction product obtained at 350_C and 27.3 to 35.5 MPa, CO initial pressure was 5 MPa (Elliott et al, 1988). [e] n/a = not available.…”

“…The analytical results of 78 samples showed that the raw TCC oil products had an average elemental composition of 71.1% carbon, 8.97% hydrogen, 4.12% nitrogen, 0.2% sulfur, and 3.44% ash t is very important that biomass-derived oils are characterized in order to utilize them directly as fuel or for further upgrading. The chemical compositions of the biomass-derived oils are complicated and extensive numbers of compounds have been reported (Elliott et al, 1988;Pakdel and Roy, 1988;Piskorz et al, 1988;Maggi and Delmon, 1994;Sipila et al, 1998). The chemical and physical stability of the biomass-derived oils are also important for long-time storage (Adjaye et al, 1992).…”

“…The water content of the pyrolytic liquids ranged from 18% to 20% by weight. Elliott et al (1988) analyzed and compared the elemental compositions of several liquefaction oils from different high-moisture (90%-95%) biomass feedstocks. Their results showed that the process yields varied from 19.2% to 34.7% and the biomass-derived oils had a similar carbon and hydrogen content of 75% and 9%, respectively.…”

“…The raw TCC oil was readily separated by gravity from the post-processed water that contained some water-soluble components from the feedstock and from the depolymerization of swine manure. Organic solvent extraction, which was usually used for the recovery of liquefaction oils from some biomass conversion processes (Boocock et al, 1980;Elliott et al, 1988), was not necessary for the TCC process.Seventy-eight oil samples produced by the TCC process using CO as the process gas and under different operating conditions were analyzed to determine the elemental composition of carbon, hydrogen, nitrogen, and sulfur. The average carbon content in the raw TCC oil samples was 71.1%, hydrogen 9.0%, nitrogen 4.1%, and sulfur 0.2%.…”