The Key Applications and Technological Advances of Diatomite Supports in the Catalyst Industry

Analysis of the Characteristics of Diatomite Supports and Their Compatibility with the Catalyst Industry

Diatomite supports, as a natural porous siliceous material, hold a significant position in the catalyst industry. This special support, formed by the deposition of ancient diatom fossils, mainly consists of amorphous silica (with a SiO₂ content of 85-94%), featuring a unique combination of physical and chemical properties: high porosity (60-90%), large specific surface area (20-70 m²/g), suitable pore size distribution (5-100 nm), and excellent chemical and thermal stability (with a maximum temperature resistance of 1000°C). These characteristics of diatomite supports make them ideal carrier materials for various catalytic reactions.

In catalyst design, diatomite supports mainly enhance catalytic performance through three mechanisms: first, they provide highly dispersed active site anchoring points to prevent metal particles from sintering; second, they optimize the mass transfer efficiency of reactants and products through multi-level pore structures; third, they utilize the strong interaction between surface silanol groups and active components (SMSI effect). Studies have shown that catalysts based on diatomite supports can increase the dispersion of active components by 30-50% and extend the catalytic life by 2-3 times. 

The application of diatomite carriers in various catalysts

Diatomite carriers in petrochemical catalysts

In the petroleum refining and chemical processes, diatomite carriers serve as catalyst substrates and have significant advantages. Compared with traditional alumina carriers, diatomite carriers have more balanced acidity and alkalinity, better thermal stability, and superior anti-carbon deposition performance. Experimental data show that the reforming catalyst containing diatomite carriers maintains an activity retention rate of over 85% after running at 650°C for 1000 hours, which is 20-30% higher than that of traditional catalysts.

The application of diatomite carriers in hydrogenation desulfurization (HDS) catalysts is particularly successful. Through special surface modification treatment, diatomite carriers can simultaneously load various active components such as Mo, Co, and Ni without mutual inhibition. After a refinery adopted diatomite carrier-based HDS catalyst, the sulfur content in diesel decreased from 500 ppm to below 10 ppm, and the catalyst operation cycle was extended by 40%.

Silicon dioxide carriers in environmental catalysts

In the fields of vehicle exhaust treatment and industrial waste gas purification, the main functions of silicon dioxide carriers are as follows: providing high specific surface area to support precious metal active components; optimizing the pore structure of the catalyst to enhance gas diffusion efficiency; enhancing the catalyst's resistance to poisoning. The silicon dioxide carriers with controlled pore size (10-50 nm) can form ideal three-dimensional贯通 pores， significantly reducing the internal diffusion resistance of the catalytic reaction.

Studies have shown that the starting temperature (T50) of automotive three-way catalysts with silicon dioxide carriers as the base can be reduced by 20-30°C， and the amount of precious metals can be reduced by 15-20%， fully meeting the requirements of the sixth emission standard. In VOCs purification catalysts， the silicon dioxide carriers not only play a supporting role， but their surface acidic sites can also promote the adsorption and activation of organic substances， increasing the conversion rate of toluene by 25-35%.

Silicon dioxide carriers in fine chemical catalysts

In the synthesis of fine chemicals such as pharmaceuticals and pesticide intermediates, silicon dioxide carriers demonstrate unique value. By regulating the surface chemical properties of the silicon dioxide carriers, highly selective catalytic systems can be developed. Tests have shown that the Pd catalyst loaded on the amino-modified silicon dioxide carriers exhibits a selectivity of over 95% for C=O bonds in hydrogenation reactions, which is much higher than that of conventional carriers.

In asymmetric synthesis catalysts, the chiral modification of silicon dioxide carriers opens up new avenues. By anchoring chiral ligands on the surface of the silicon dioxide carriers, the prepared immobilized catalysts not only maintain high enantiomeric selectivity (ee value > 90%), but can also be reused more than 10 times without a decrease in activity, significantly reducing the cost of chiral catalysts. 

Technological Innovation and Performance Optimization of Diatomite Supports

Surface Modification Technology

To enhance the performance of diatomite supports in catalytic applications, various surface modification techniques have been developed in the industry:

1. Acid treatment activation: Using hydrochloric acid or sulfuric acid to increase the density of surface silanol groups and enhance the concentration of acidic sites;

2. Metal oxide modification: Adjusting the surface properties and electronic effects through oxide coatings such as TiO₂ and ZrO₂;

3. Doping with heteroatoms: Introducing heteroatoms such as Al and B to regulate the acidity and basicity of the support;

4. Organic functionalization: Introducing specific functional groups (such as -NH₂, -SH) using silane coupling agents.

Structural control technology

Optimize the microstructure of diatomite carriers through physical and chemical methods:

Sintering treatment: Sintering at 500-900°C to adjust pore structure and surface activity;

Grading technology: Achieve particle size distribution suitable for different reactions (typically 50-200 μm for catalytic grade);

Pore channel engineering: Directionally regulate pore size distribution through template method or chemical corrosion.

Composite reinforcement technology

Composite diatomite carriers with other functional materials:

Compared with molecular sieves: Such as ZSM-5/diatomite carrier composites, which have advantages of shape-selective catalysis and mass transfer;

Compared with carbon materials: Such as carbon nanotubes reinforced diatomite carriers, which improve conductivity and mechanical strength;

Compared with magnetic materials: Such as Fe₃O₄@diatomite carriers, which facilitate magnetic separation and recovery.

The performance tests have shown that the optimized silica soil carrier can increase the dispersion degree of the active component by 50-80% and enhance the catalytic efficiency by 30-50%. For instance, the Pd catalyst loaded on the modified silica soil carrier maintains a selectivity of over 95% for the C=O bond when the conversion rate reaches 99% in the selective hydrogenation of cinnamaldehyde. 

Application Cases and Effect Evaluation

Petrochemical Hydrogenation Catalyst Case

After adopting the diatomite carrier-based hydrogenation refining catalyst in a certain refining and chemical enterprise, remarkable results were achieved:

- The cetane number of diesel increased by 3-5 units;

- The pressure drop of the catalyst bed decreased by 30-40%;

- The operating cycle was extended from 12 months to 18 months;

- The catalyst consumption per unit product decreased by 25%, and annual cost savings exceeded 20 million yuan.

Automobile Exhaust Purification Case

In the catalytic converter of vehicles meeting the national VI standards, the diatomite carrier catalyst performed well:

- The ignition temperatures of CO, HC, and NOx decreased to 180℃, 200℃, and 220℃ respectively;

- The usage of precious metals (Pt, Pd, Rh) decreased by 20%;

- The service life exceeded 160,000 kilometers;

- The system back pressure decreased by 15%, and fuel economy improved.

Pharmaceutical Intermediate Synthesis Case

The diatomite carrier catalyst used in the synthesis of a certain antibiotic intermediate:

- The reaction selectivity increased from 88% to 96%;

- The number of catalyst reuses increased from 5 times to 15 times;

- The product purity reached over 99.9%;

- The waste generation was reduced by 60%, and it met GMP requirements more fully. 

Performance comparison data

Compared with traditional catalyst carriers, the silica soil carrier product performs exceptionally well in multiple indicators:

| Performance indicator | Silica soil carrier catalyst | Traditional carrier catalyst |

| Active component dispersion | High (50-80%) | Medium (30-50%) |

| Thermal stability | Excellent (1000°C) | Good (800°C) |

| Anti-carbon deposition ability | Excellent (low carbon deposition rate by 30%) | Average |

| Mass transfer efficiency | High (low internal diffusion resistance) | Varies depending on the carrier |

| Cost-effectiveness | Moderately high | Varies greatly depending on the type | 

Industry Development Trends and Challenges

Technical Development Trends

1. Atomic-level Dispersion: Develop single-atom siliceous soil carrier catalysts to achieve 100% atomic utilization rate;

2. Intelligent Response: Research environmental-responsive siliceous soil carrier catalytic systems;

3. Multi-functional Integration: Endow siliceous soil carriers with catalytic-separation-sensing and other composite functions;

4. Green Manufacturing: Optimize the processing technology of siliceous soil carriers to reduce energy consumption and emissions.

Market Development Prospects

The global catalyst market is expected to reach 45 billion US dollars by 2025, with an annual growth rate of approximately 5.5%. Due to its superior performance, the share of silica soil carriers in the catalyst carrier market is expected to increase from the current 15% to 25%. Particularly in the following areas, the growth potential is enormous:

- Biomass conversion catalysts;

- Electro-catalytic materials;

- Photocatalysts;

- Catalytic technologies related to carbon neutrality.

Technical Challenges Faced

1. Precise Structure Control: Achieving precise regulation of the pore structure of silica soil carriers;

2. Structure-Effect Relationship: Deeply understanding the interaction mechanism between carriers and active components;

3. Standardization System: Establishing performance evaluation standards for silica soil carrier catalysts;

4. Large-scale Production: Solving the problem of batch production of high-performance silica soil carriers.

As catalytic science progresses towards atomic-level precise control and greenification, the significance of diatomite carriers in the catalyst industry will continue to increase. Through interdisciplinary innovation and cooperation between academia, industry and research, diatomite carriers are expected to become the core substrate of the next generation of high-performance catalysts, providing key technical support for important fields such as energy and chemical engineering, and environmental protection. It is predicted that in the next five years, the market demand for diatomite carriers for catalysts will grow at an average annual rate of 7-9%, and technological progress will drive their breakthrough applications in more advanced catalytic fields.