Torrefaction at 200 °C of Pubescens Pretreated with AlCl₃ Aqueous Solution at Room Temperature

Abstract

Metal salt soaking–torrefaction conversion technology was investigated. It was found that AlCl 3 pretreatment of pubescens favored observably the yield of liquid and small-molecular products in torrefaction via changing the composition and structure of the raw material. The maximum conversion of pretreated samples, washed (PSW) and Y liquid were 15.5 and 10.8 wt % (with 0.26 wt % monosaccharides, 0.26 wt % carboxylic acids, 0.38 wt % furan compounds, and 1.28 wt % phenols), where 20.4 wt % hemicellulose, 22.9 wt % cellulose, and 5.7 wt % lignin were converted, respectively. However, for pretreated samples (PS), the maximum conversion and Y liquid reached 44.2 and 32.1 wt %, respectively, along with 96.0 wt % hemicellulose and 31.8 wt % cellulose converted, yielding 2.39 wt % monosaccharides, 5.14 wt % carboxylic acids, 2.60 wt % furan compounds and 10.52 wt % phenols, indicating obvious catalytic effects of residual AlCl 3 on the decomposition of the three major components in torrefaction. Two-dimensional HSQC and electrospray ionization mass spectrometry (ESI-MS) characterizations further confirmed the dominant formation of oligomers derived from holocellulose, lignin, and cross-linkage involving the lignin–carbohydrate complex, indicating that the catalytic thermal cleavage of β-O-4, C-O-C, β-β, 5–5, 4-O-5, C α –C β , and α-O-4 linkages by aluminum species in the samples benefited the yield of liquid as well as monophenols.

Pyrolysis of High-Ash Natural Microalgae from Water Blooms: Effects of Acid Pretreatment

“…GC-TCD was used to determine the relative contents of gaseous products, which were collected by a gas bag during the whole pyrolysis process. The samples were tested by GC9710 (Fuli) equipped with a TCD detector and a TDX-1 carbon molecular sieve packed column (2 m × 3 mm id) [ 52 ]. The main chromatographic parameters were as follows: carrier gas, nitrogen; carrier gas flow rate, 20 mL/min; inlet temperature, 145 °C; column temperature, 120 °C; detector temperature, 180 °C.…”

Effect of Ni(NO3)2 Pretreatment on the Pyrolysis of Organsolv Lignin Derived from Corncob Residue

“…Meanwhile, the detector voltage of instrument was 1.60 kV. The collision-induced dissociation (CID) energy for MS/MS was 25% [20]. Before the test, a small amount of bio-oil was obtained with a capillary pipet and then diluted by methanol to about 2 mL.…”

“…GC-TCD was used to determine the relative contents of gaseous products. The samples were tested by GC9710 (Fuli, Taizhou, China) equipped with a TCD detector and a TDX-1 carbon molecular sieve packed column (2 m × 3 mm id) [20]. The temperatures of column, detector and oven were maintained at 120, 145 and 160 • C, respectively.…”

“…These compounds could be obtained through different mechanism of chemical bond cleavage in pyrolysis. According to literature [20,29,38], phenol, guaiacol, and syringol were acquired by the cleavage of C 1 -C α from primary units in lignin structure, while monophenols with methyl at C 4 position were mainly derived from the breakage of C α -C β in the side chain. Meanwhile, monophenols with ethyl at C 4 position were obtained from the breakage of C β -C γ while monophenols with vinyl at C 4 position could be attributed to the cracking of C β -C γ and the dehydration of C α -OH.…”

“…Among these methods, pretreatment with inorganic salt solution is an outstanding and feasible means due to high efficiency and low cost [10,19]. Wang et al [20] proposed a new conversion method called salt soaking−torrefaction. It was discovered that the pretreatment of AlCl 3 could stimulate the depolymerization of pubescens when torrefied at 200 • C, obtaining more bio-oil and phenolic monomers.…”