Related Experiment Video
Updated: Aug 18, 2025
09:21
Tuning the Acidity of Pt/ CNTs Catalysts for Hydrodeoxygenation of Diphenyl Ether
Published on: August 17, 2019
9.0K
TiO2 Catalyzed Dihydroxyacetone (DHA) Conversion in Water: Evidence That This Model Reaction Probes Basicity in
Insaf Abdouli1, Frederic Dappozze1, Marion Eternot1
1Institut de Recherches sur la Catalyse et l'Environnement de Lyon, UMR 5256, CNRS, Université Claude Bernard Lyon 1, IRCELYON, F-69626 Villeurbanne, France.
Molecules (Basel, Switzerland)
|December 11, 2022
Summary
Dihydroxyacetone (DHA) conversion over titanium dioxide (TiO2) catalysts is sensitive to both acidity and basicity. Basic sites promote fructose formation, while acid sites yield pyruvaldehyde and lactic acid.
Area of Science:
- Catalysis
- Materials Science
- Chemical Engineering
Background:
- Dihydroxyacetone (DHA) conversion is a key reaction in various chemical processes.
- Titanium dioxide (TiO2) catalysts exhibit both acidic and basic properties, influencing reaction pathways.
- Understanding the role of acid-base sites is crucial for optimizing DHA conversion.
Purpose of the Study:
- To investigate the influence of TiO2 catalyst acidity and basicity on the aqueous conversion of dihydroxyacetone (DHA).
- To elucidate the parallel reaction pathways involved in DHA transformation.
- To correlate catalyst properties with product selectivity.
Main Methods:
- Utilized a series of six commercial TiO2 samples with varying structures and textures.
- Employed gas-phase characterization techniques (FTIR, microcalorimetry) to analyze acid-base properties using pyridine, NH3, and CO2 adsorption.
- Confirmed findings with reference acid (niobic acid) and base (hydrotalcite) catalysts.
Main Results:
- DHA conversion proceeds via two parallel pathways: acid-catalyzed (producing pyruvaldehyde and lactic acid) and base-catalyzed (producing fructose).
- A linear correlation was observed between initial hexose formation rates and total basic site density, indicating water-tolerant basic sites.
- Rutile TiO2 samples exhibited the highest basicity.
- Only strong Lewis acid sites on TiO2 were water-tolerant and effective for pyruvaldehyde and lactic acid production.
Conclusions:
- Both acidity and basicity of TiO2 catalysts significantly impact DHA conversion pathways and product distribution.
- Basic sites play a crucial role in DHA condensation to hexoses, even in aqueous media.
- Optimizing the balance of acid-base properties is essential for selective DHA conversion using TiO2 catalysts.
Keywords:
CO2 and NH3 microcalorimetryFTIR of pyridine adsorptionaciditybasicitydihydroxyacetonetitanium dioxideMore Related Videos
Related Concept Videos
01:13Esters to Carboxylic Acids: Acid-Catalyzed Hydrolysis
3.1K
Hydrolysis of esters under acidic conditions proceeds through a nucleophilic acyl substitution. In the presence of excess water, the reaction proceeds in a reversible manner, forming carboxylic acids and alcohols.
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...
3.1K
01:17Solution Composition During Acid/Base Titrations
662
The titration of a weak acid with a strong base results in the formation of water and the conjugate base of the acid. For instance, titrating acetic acid with sodium hydroxide leads to the formation of water and sodium acetate. A solution of acetic acid and sodium acetate constitutes a buffer whose relative concentration at different stages of the titration is indicated by the α values, which represent percentages of the weak acid and its conjugate base.
The α0 and α1 values...
The α0 and α1 values...
662
01:01Acid Halides to Carboxylic Acids: Hydrolysis
2.8K
Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic...
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic...
2.8K
01:20Aldehydes and Ketones with Water: Hydrate Formation
3.4K
An oxygen-based nucleophile, like water, can undergo addition reactions with aldehydes and ketones. The reaction leads to the formation of hydrates, also referred to as 1,1-diols or geminal diols.
The formation of hydrates is a reversible reaction. Hydrate formation is influenced by steric and electronic factors accompanying the alkyl substituents on the carbonyl group: The rate of hydrate formation increases with a decrease in the number of alkyl groups attached to the carbonyl carbon. Hence,...
The formation of hydrates is a reversible reaction. Hydrate formation is influenced by steric and electronic factors accompanying the alkyl substituents on the carbonyl group: The rate of hydrate formation increases with a decrease in the number of alkyl groups attached to the carbonyl carbon. Hence,...
3.4K
01:18Titration of Polyprotic Base with a Strong Acid
846
The titration of a polyprotic base such as sodium carbonate with a strong acid such as hydrochloric acid results in two equivalence points on the titration curve. At the first equivalence point, the carbonate ions in the base are completely converted to bicarbonate ions. The second equivalence point corresponds to the complete conversion of bicarbonate ions to carbonic acid, which dissociates into carbon dioxide and water. The region before the first equivalence point corresponds to the...
846
01:07Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis
3.5K
Acetoacetic ester synthesis is a method to obtain ketones from alkyl halides and β-keto esters. The reaction occurs in the presence of an alkoxide base that abstracts the acidic proton of the β-keto esters. The step results in an enolate ion which is doubly stabilized. The enolate then reacts with an alkyl halide via the SN2 process to produce an alkylated ester intermediate with a new C–C bond. The hydrolysis of the intermediate, followed by acidification, results in an...
3.5K