Efficient and Re-usable SAPO Catalyst for the Selective Production of Furans from Biomass

Efficient and Re-usable SAPO Catalysts for the Selective Production of Furans from Biomass

Prasenjit Bhaumik and Paresh Laxmikant Dhepe*Catalysis & Inorganic Chemistry Division, CSIR-National Chemical Laboratory, Pune-411008, India

E-mail: pp.bhaumik@ncl.res.in, pl.dhepe@ncl.res.in, Phone: +91-20-2590-2024, Fax: +91-20-2590-2633

Introduction

Reaction Scheme

Toluene

Water

Conclusions References

AcknowledgementAuthors thank Department of Science & Technology (DST), India for funding.

P. Bhaumik thanks University Grant Commission (UGC), India for research fellowship.

Objectives

Figure. Catalyst evaluation for furfural synthesis from hemicellulose.Reaction condition: hemicellulose (5 wt%), catalyst, water+toluene(1:1 v/v), 170oC, 8 h.

SAPO-44 is the best catalyst among other catalysts studiedFurfural yield=63%, mass balance=88%.

Figure. Recycle study of SAPO-44. Reaction condition: hemicellulose(5 wt%), SAPO-44, water+toluene (1:1 v/v), 170oC, 8 h.

In recycle runs SAPO-44 was directly reused after only waterwashing. SAPO-44 is highly stable catalyst and could be reusedminimum 8 times without lossing its activity.

Figure. Catalyst evaluation for HMF synthesis from fructose.Reaction condition: fructose (10 wt%), catalyst, water+MIBK (1:5 v/v),175oC, 1 h.

SAPO-44 is the best catalyst among other catalysts studied.Furfural yield=78%, selectivity=88%.

Figure. Recycle study of SAPO-44. Reaction condition: fructose (10 wt%),SAPO-44, water+MIBK (1:5 v/v), 175oC, 1 h.

In recycle runs SAPO-44 was reused after calcination at 550oC for 12 h.SAPO-44 shows slight change in activity upto 3rd run and afterwards its activityremains constant minimum upto 5th run.

Figure. XRD patterns for SAPO’s.

XRD patterns for SAPO’s well matches with literature.XRD patterns remain similar in both fresh and spent SAPO-44used in hemicelllose to furfural reaction.Spent SAPO-44 used in fructose to HMF reaction shows all thepeaks in its position with lowering in some peak intensity.

Figure. NH3-TPD profile for fresh and spent SAPO-44.

Both fresh and spent SAPO-44 used for furfuralsynthesis shows similar total acid amount (1.2 mmol/g)with similar acid amount distribution.Absence of strong acid site and lowering of weak acid site(0.5 mmol/g) is observed in spent SAPO-44 (HMF work).

Figure. Solid state NMR study for fresh and spent SAPO-44.

In case of fresh and spent SAPO-44 (furfural), similar peakpatterns with similar intensity is seen for 29Si and 27Al NMR spectra.29Si NMR spectra of spent SAPO-44 (HMF) shows presence of all theSi-environments with change in intensity.

Figure. Hydrophilicity-hydrophobicity study.

SAPO’s are more hydrophilic than HMOR.

Table. Elemental analysis and N2-sorption study.

Amount of Al and P present in both fresh and spent SAPO-44remains similar.Surface area remains similar in SAPO-44 used in furfural synthesis butit decreases in case of HMF reaction.

Figure. SEM images for SAPO’s.

All the SEM images matches well to the literature reports.Spent SAPO-44 (both furfural and HMF) shows similar cubicmorphology with similar cubic edge length (ca. 3.16 um) to that ofthe fresh SAPO-44 (3.13 um).

∗ SAPO-44, SAPO-5 and SAPO-11 with varies structure type, acid amount, acid site distribution porediameter, surface area aresynthesized and utilized in the synthesis of important furan compounds.

∗ SAPO-44 is highly active in the synthesis of furfural (63%) directly from hemicellulose.

∗ SAPO-44 is re-usable minimum upto 8 runs without loosing its activity in furfural synthesis.

∗ Various physico-chemical characterizations confirms the structural stability of SAPO-44.

∗ SAPO-44 is also highly active in the synthesis of HMF from mono-, di- and poly-saccharide.

∗ Recycle study shows slight change in SAPO-44 activity upto 3rd run and afterwards similar activity minimum upto 5th run.

∗ ICP-OES data confirms the reposition of Si, Al and P within the structure without leaching which leads to theslight morphologicalchange in SAPO-44 used in HMF reaction.

1. A. Fukuoka and P. L. Dhepe, Angew. Chem. Int. Ed., 2006, 45, 5161.2. E. I. Gurbuz, J. M. R. Gallo, D. M. Alonso, S. G. Wettstein, W. Y. Lim and J. A. Dumesic, Angew. Chem. Int. Ed., 2013, 52, 1270.3. P. L. Dhepe and R. Sahu, Green Chem., 2010, 12, 2153.4. R. Sahu and P. L. Dhepe, ChemSusChem, 2012, 5, 751.5. P. Bhaumik and P. L. Dhepe, ACS Catal., 2013, 3, 2229.6. P. Bhaumik and P. L. Dhepe, RSC Adv., 2013, 3, 17156.

∗ To synthesize solid acid catalyst which may help in hydrolysis and dehydration reaction to yield furans.

∗ To synthesize hydrothermally stable catalyst which may help to keep catalyst morphology unaltered.

Synthesis Properties

Physico-Chemical Characterizations

Utilization in Furfural Synthesis

Mixture of Si-, Al- and P- precursors

Silicoaluminophosphate

Hydrothermal 200oC

Table. Synthesis details for SAPO’s. Table. Properties of SAPO’s.

Figure. TGA-DTG study for SAPO-44 in air atmosphere.

TGA-DTG study shows that SAPO-44 looses 7.8% mass at 92.7oC due to lossof water and at 400oC 0.8% mass loss is the indicative for remaining SDA loss.This study confirms the structural stability of SAPO-44 upto 1000oC.

∗ Biomass conversion to value-added chemicals using solid acid catalyst is known.1

∗ Furans (furfural and 5-hydroxymethylfurfural, HMF) are valuable platform chemicals and they have various applications in thesynthesis of a range of other chemical intermediate and fuel.

∗ Two-pot method for the synthesis of furfural or C5 sugars from hemicellulose is reported but it shows an additional step for thetransformation of hemicellulose to oligomers and C5 sugars.2

∗ In our group, we have developed one-pot method for the first time for direct conversion of hemicellulose to C5 sugars or furfuralusing zeolite (silicoaluminate) as catalyst. The product distribution depends on the solvent system.3, 4

∗ Zeolites are highly active for the furfural synthesis but its morphology changes during reaction leading to lowering the yield.

∗ To improve the catalytic system recently we have developed silicoaluminophosphate (SAPO) based reaction system.

∗ SAPO-44 is highly active and stable under reaction condition and produces furfural in similar yield over minimum 8 recycle runs.5

∗ SAPO-44 can be used for the selective production of HMF from variety of substrates (poly-, di- and mono-saccharides).6

Utilization in HMF Synthesis

OO

Furfural

OOO

HO OO

HO OO

OO

HO

OOHO

HO

O

OH

OH

OH

OH

HO2C

O

O

OH

HO

OHSolid acid O

OHHOHO

OH

O

OH

OH

HO

HO

L-ArabinoseHemicellulose

H2O, -3H2O,+

D-Xylose

Solid acid

Poly-saccharideSolid acid

H2O,Di-saccharide

Solid acid

H2O,

OHOHO

OH

OH

OH

Lewis acid

Isomerization

OO

OHO

OHHO

OH

HOOH

-3H2O,

Solid acid

Glucose Fructose HMF