Aldol Condensations Using Bio-oil Model Compounds: The Role of Acid–Base Bi-functionality

Abstract

The aldol condensation of acetaldehyde, acetone, and methyl ethyl ketone, which represent model biooil compounds, in the condensed phase, was performed using a bi-functional aluminophosphate catalyst. It was found that increasing the number and strength of the basic sites while decreasing acid sites on the catalyst caused a reduction in yield of the condensation products. In contrast, the addition of organic acids such as acetic acid at low concentrations to the catalyst-containing reaction mixture was found to increase activity. The presence of both acid and base sites was found to be necessary and their relative number was important for both the activity and selectivity of the condensation reaction. A mechanism explaining the observed phenomena was proposed.

Scaling‐Up of Bio‐Oil Upgrading during Biomass Pyrolysis over ZrO2/ZSM‐5‐Attapulgite

“…[47][48][49][50] In the reactionc atalyzed by ZrO 2 /n-ZSM-5-ATP (Figure 3a,b), styrene oligomers were formed, but to a lower extent than over the n-ZSM-5 ( Figure 3c)a nd ZrO 2 /n-ZSM-5 ( Figure 3d)c atalysts. The intensity evolution of the cyclic oligomers (7), favored in zones with high densities of Brønsted acid sites, was particularly low for the ZrO 2 /n-ZSM-5-ATPc atalyst. On the contrary,t he formation of linear dimer (5) was more pronounced, especially in the first 5min of the reaction;a fterwards, the relative amount of trimero ligomers (6a and 6b)i ncreased.…”

“…The optimum conditions for maximizing the yield of the liquid fraction (bio-oil) comprise intermediate temperatures, typically in the range 500-600 8C, and high heatingr ates (fast pyrolysis). [2,[5][6][7][8][9] In most cases, these transformations are aimed to reduce( at least partially) the oxygen content of the bio-oil, thus bringing its chemical compositionc loser to that typical of fossil-derived fuels. [4] Bio-oil upgradinghas been investigated by avariety of physical and chemical methods.…”

“…Chemical transformations applied to the bio-oil include catalytic pyrolysis, hydrodeoxygenation, ketonization,a ldol condensation, esterification, and alkylation. [2,[5][6][7][8][9] In most cases, these transformations are aimed to reduce( at least partially) the oxygen content of the bio-oil, thus bringing its chemical compositionc loser to that typical of fossil-derived fuels. Catalytic pyrolysis presents the advantage of operating at atmospheric pressure and can thus be easily combined with the biomass thermal step.…”

Comparative Study on Catalytic and Non-Catalytic Pyrolysis of Olive Mill Solid Wastes

“…This is the first study in which fast pyrolysis is comparatively 163 assessed with catalytic pyrolysis for olive husk/kernels. (Deng et al 2006, Gaertner et al 2009, Mante et al 2015, Snell et al 2010). Prior to the 194 experiments, the catalytic materials were calcined at 500 °C for 3 h and stored in a desiccator.…”

“…The MgO (5% Co) catalyst that are catalysed by the basic sites of the catalyst (Deng et al 2009, Snell et al 2010). …”