CATALYSTS
Precursor chemistry & catalyst synthesis
Equally important is the choice of the precious metal component in form of a salt or precursor. Heterogeneous platinum, palladium and ruthenium catalysts can be synthesised from a range of precursor types, including chlorides, nitrates, and acetates, each exhibiting distinct reduction behaviour and nucleation kinetics. The precursor ultimately determines metal nanoparticle size distribution, crystallite sizes, oxidation state and the degree of metal – support interaction, all of which significantly affect catalyst performance and longevity.
Most importantly, combining these two ingredients using the correct synthesis method results in a final catalyst with the desired physical properties. Even subtle changes in the synthesis sequence, such as the pH during impregnation, the drying rate, the reduction atmosphere or the temperature, can lead to significant differences in metal dispersion and catalytic outcomes.
Consequently, catalysts designed with identical nominal loadings may exhibit markedly different properties, resulting in variations in reaction kinetics and sensitivity to deactivation, and thus process compatibility. The frequently cited example of‘ 5 wt % Pd / C’ therefore illustrates that nominal specifications neither capture the complexity of catalyst design nor reliably predict catalytic performance in a given application.
Process performance
In industrial hydrogenation processes, catalyst performance is defined not only by intrinsic catalytic activity but also by operational characteristics that influence process efficiency.
Filtration behaviour, for example, can vary considerably between different carbon supports. Particle size distribution, bulk density and
Heraeus’ precious metals loop
cake permeability influence filtration rates and, therefore, batch cycle times. Supports with lower bulk density may enable faster filtration, while differences in wettability influence catalyst dispersion and washing efficiency.
Catalyst stability is another critical factor. Deactivation mechanisms, such as poisoning, coke formation, nanoparticle sintering or metal leaching, are well documented in heterogeneous catalysis. These processes can gradually reduce activity, alter selectivity, and affect reproducibility over the course of multiple reaction cycles. For process operators, this means that catalyst selection must consider the interaction between catalyst design and the specific reaction environment, including substrates, solvent systems, and operating conditions.
Integrating design in production
To navigate these complexities, Heraeus Precious Metals combines broad access to diverse carbon carriers and precursor options via a global network of activated carbon suppliers with the ability to integrate and combine these variables in a systematic and applicationoriented manner.
The materials include high-BET carbons( e. g. based on coconut shell), low-impurity acid-washed variants and structurally tailored support grades. This diversity is essential for matching specific hydrogenation processes with carriers that offer a balance of porosity, surface chemistry, filtration behaviour and mechanical stability.
In addition, the company produces precious metal precursors inhouse and can make platinumgroup metal salts at scale. This integration enables tight control over precursor quality, availability and consistency. Because precursor chemistry directly influences the catalysts microstructure, the ability to adjust precursor properties on demand is crucial
Heraeus Precious Metals operates a global manufacturing network that supports both catalyst development and industrial supply. This includes production facilities at its headquarters in Europe and at the Ravindra Heraeus joint venture in India. Their integration into Heraeus’ global network enables expanded manufacturing capabilities and costoptimised supply options, particularly
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