Catalytic pyrolysis of cellulose employing MCM-41 type catalysts

ANDRES I. CASONI; MARIA L NIEVAS; ELIZABETH L. MOYANO; ALEJANDRA DIEZ; MARIANA ALVAREZ; MARIANA DENNEHY; MARIA A. VOLPE

APPLIED CATALYSIS A-GENERAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016

0926-860X

tThe pyrolysis of microcrystalline cellulose in contact with MCM-41 and Fe−, Al−and Cu−substitutedsamples was carried out at 400◦C in a fixed-bed glass reactor in order to obtain high bio-oils yields.The acid properties of the catalysts were determined by potentiometric titration with n-butylamine,while the redox properties were studied by TPR. BET surface area, pore volume and pore size weremeasured by means of N2sorptometry. The effect of the different catalysts on the composition of the bio-oils was analyzed in the light of the characterization results. Mainly the concentration of levoglucosan(LG), levoglucosenone (LGO), 1,4:3,6-dianhydro--d-glucopyranose (DGP) and (1S,5R)-5-hydroxy-3,7-dioxabicyclo[3.2.1]octan-4-one (LAC) were measured. The presence of the solid catalysts increased theliquid formation and strongly modified the chemical composition of the bio-oils compared to the non-catalytic pyrolysis. All the catalysts decreased the production of LG and increased that of LGO, LAC andDPG. The mild acidity of the catalysts promoted dehydration reactions, while redox properties led to ahigher production of isomerization products. A much higher LGO yield was obtained over Al-MCM-41(53 wt% of cellulose is converted to LGO over this catalyst) than by non-catalytic pyrolysis of cellulosepreviously washed with phosphoric acid (7 wt% of washed cellulose is converted to LGO). In order toevaluate the reuse of the catalyst, the spent sample was submitted to calcination at 400◦C. The physico-chemical properties were not modified after the calcination treatment and the pyrolysis employing thespent sample led to a similar bio-oil composition (though with a smaller yield) as in the case of the freshcatalyst. A second regeneration of the catalyst diminished the specific surface area and the surface acidity.Concomitantly a notable decrease of the yield of LGO was observed.