Fast pyrolysis of microcrystalline cellulose (MC) was carried out by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The effects of temperature, time, and a catalyst on the distribution of the pyrolysis products were analyzed. The reaction temperature and time can significantly affect the types and yields of compounds produced by cellulose pyrolysis. A pyrolysis temperature of 500–600 °C and pyrolysis time of 20 s optimized the yield of volatile liquid in the pyrolysis products of cellulose. In all catalytic experiments, the relative contents of alcohols (1.97%), acids (2.32%), and esters (4.52%) were highest when K₂SO₄ was used as a catalyst. HZSM-5 promoted the production of carbohydrates (92.35%) and hydrocarbons (2.20%), while it inhibited the production of aldehydes (0.30%) and ketones (1.80%). MCM-41 had an obvious catalytic effect on cellulose, increasing the contents of aldehydes (41.58%), ketones (24.51%), phenols (1.82%), furans (8.90%), and N-compounds (12.40%) and decreasing those of carbohydrates (5.38%) and alcohols (0%).

It is important to clarify the distribution of pyrolysis products from lignocellulosic biomass for its thermal transformation to produce high-quality bio-oil. Influences of the reaction temperature and catalysts on the pyrolysis product distribution from aspen wood (AW) and rice husk (RH) were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The difference in components from the lignocellulosic biomass results in different pyrolysis characteristics of the biomass raw materials. The reaction temperature significantly influences the product distribution from AW and RH pyrolysis. In all AW catalysis experiments, acids (8.35%), ketones (3.79%), phenols (4.73%), and esters (1.50%) have the lowest content while carbohydrates (48.75%) demonstrate the highest content when taking zinc chloride (ZnCl₂) as the catalyst; the HZSM-5 molecular sieve (HZSM-5) promotes the generation of esters (7.97%) and N-compounds (22.43%) while inhibiting production of aldehydes (2.41%); addition of an MCM-41 molecular sieve (MCM-41) is conducive to increasing the contents of aldehydes (21.29%), furans (5.88%), ketones (22.30%), acids (20.46%), and hydrocarbons (4.85%), while reducing the contents of alcohols (0) and carbohydrates (0). In all RH catalysis experiments, the addition of ZnCl₂ helps increase the content of carbohydrates (39.16%) and decrease the contents of ketones (3.89%), phenols (5.20%), alcohols (2.34%), esters (1.13%), and N-compounds (3.09%); when applying HZSM-5 as the catalyst, hydrocarbons (18.28%) and alcohols (6.66%) reach their highest content while acids (13.21%) have the lowest content; MCM-41 promotes the generation of aldehydes (25.33%) and furans (5.55%) while inhibiting that of carbohydrates (1.42%).

Torrefaction is an effective method for upgrading biomass. Cedar torrefaction is carried out in a fixed bed reactor at the temperature of 200–300 °C. The structural parameters are obtained from elemental analysis and ¹³C nuclear magnetic resonance (NMR). Thermal degradation behavior of raw and torrefied cedar is monitored by thermogravimetry analysis. The results show that carbon structure varied during torrefaction has a significant effect on thermal degradation of cedar. Some unstable oxygen functional groups, such as C1 of hemicellulose, β-O-4 linked bonds, and amorphous C6 of cellulose, are decomposed at mild torrefaction of torrefied temperature ≤ 200 °C. The temperature of maximum weight loss rate increases from 348 °C of raw cedar to 373 °C of C-200. The amorphous cellulose is partly re-crystallized at moderate torrefaction of torrefied temperature 200–250 °C. The aromaticity of torrefied cedar increases from 0.45 of C-200 to 0.73 of C-250. The covalent bond in the side chain of aromatic rings in cedar was further broken during torrefaction at severe torrefaction of torrefied temperature 250–300 °C. The area percentage of DTG mainly signed at 387 °C of C-300. The proton aromatic carbon increases from 12.35% of C-250 to 21.69% of C-300. These results will further facilitate the utilization of biomass for replacing fossil fuel to drive carbon neutrality.