Introduction & Motivation

Substantial production of oxygenates from biomass conversion and biodiesel production create interest in upgrading these compounds to gasoline range products, among others. Glycerol is the byproduct of biodiesel production and also is a model for polyol sugar compounds in biomass. In order to utilize glycerol, dehydration and oligomerization over acidic zeolites is proposed.

In previous results, we have found that glycerol can be directly converted to aromatics up to 60% yield on HZSM5 (Si/Al=45) via a well known oligomerization process.

HZSM5 & HZSM22 are the main zeolites that we have used for glycerol conversion. HZSM5 is the famous catalyst for the methanol to gasoline process (MTG) while HZSM22 is a catalyst that has been found to be selective in trimerization of propylene.

Objective & Approach

Convert glycerol to propanal (and other small oxygenated biomass derived molecules), that may then be oligomerized to high boiling gasoline components. 

Find conditions under which zeolites may also carry out the oligomerization to higher boiling aliphatic or aromatic gasoline components.  

Synthesize custom zeolites to tune the acidity and pore structure to achieve the most desirable products.

Reactor setup

Flow reactor: Temperature: 350-500oC Pressure: 14.7 psi Space time: 0.1-4hr (W/F) Carrier gas: H2,He

Product analysis: Online: HP6890 Gas: Carle 400 Liquid: Shimadzu Q2010 Column: HP-INNOWAX

 

Zeolite Catalyst Synthesis XRD & SEM Results

Successful synthesized HZSM22 was showed by the maching of XRD pattern (blue) and standard (black) on the left figure. SEM image on the right figure also showed needle shape as described in lituratures.

Successful synthesized HZSM5 was showed by the maching of XRD pattern (blue) and standard (black) on the left figure. SEM image on the right figure also showed cube shape as described in lituratures.

 

Catalyst Activity on Glycerol Conversion

 

Effect of temperature & space time and Catalyst stability on HZSM22

 

Proposed mechanism

Conclusions

Synthesized ZSM22 and ZSM5 successfully convert glycerol to propenal with up to 85 % yield. This is a platform feedstock for aldol condensation and oligomerization processes as well as a high value chemical product.

Glycerol produces more side products: acetaldehyde and light gases over HZSM5 and at higher temperatures and longer reaction times.

Synthesized HZSM22 exhibits robust catalyst activity and stability for propenal production.

Further hydrogenation/dehydration of propenal can be studied to make propylene, an important building block for fuels and polymer industry.