关键词: 纤维素, NaY分子筛, 催化热解, 提质, 呋喃

Abstract:

Two catalysts—MnCo₂O₄ and manganese oxide octahedral molecular sieves(OMS-2) were synthesized using co-precipitation and hydrothermal methods, respectively. On comparing these with the NaY molecular sieve for the catalytic pyrolysis of cellulose, the NaY molecular sieve was further modified to improve its catalytic activity. Co/NaY, Sn/NaY, and Co-Sn/NaY were prepared using the impregnation method.Catalytic upgrading of cellulose pyrolysis vapors for the preparation of furan compounds with different catalysts were investigated. The prepared catalysts were characterized through nitrogen adsorption-desorption, X-ray diffraction(XRD), scanning electron microscopy(SEM), and ammonia adsorption-desorption(NH₃-TPD) methods. Experimental results showed that Co or Sn metal was dispersed on the NaY surface keeping the crystal structure and morphology of NaY intact. However, the specific surface area and pore volume of the catalyst decreased after metal loading, while average pore size increased. The acidic sites of the NaY zeolite remained virtually unchanged after Sn loading, but decreased after Co loading. The specific surface area of NaY and modified NaY were much larger than those of MnCo₂O₄ and OMS-2 but the average pore size was smaller. Addition of catalysts promoted the production of alcohols, acids, and aldehydes but inhibited sugar production. The furan content increased significantly from 15.34%(non-catalytic pyrolysis) to 48.16% and 61.88% on using NaY alone and Co/NaY, respectively, albeit the mass ratio of cellulose to catalyst was 1:14. Both the Co and Sn metals-supported NaY catalysts promoted furanone production but inhibited furan production.

Key words: cellulose, NaY, catalytic pyrolysis, upgrading, furan