Honeycomb ceramic

Honeycomb ceramics are composed of countless equal holes in various shapes. At present, the largest number of holes has reached 20-40 per square centimeter, the density is 4-6 grams per cubic centimeter, and the water absorption rate is as high as 20%. Due to the characteristics of porous and thin walls, the geometric surface area of the carrier is greatly increased and the thermal shock resistance is improved. The mesh holes of the produced products are mainly triangular and square. The triangular is much better than the square, and the number of holes is also more. This is especially important as a catalyst carrier. With the increase of the number of pores per unit area and the decrease of the wall thickness of the carrier, the thermal shock resistance of the ceramic carrier increases, and the temperature of thermal shock damage also increases. Therefore, honeycomb ceramics must reduce the expansion coefficient and increase the number of pores per unit area. The coefficient of thermal expansion is the main performance index. The current foreign level is α25-1000℃≤1.0×10-6℃-1. There is a certain gap with domestic comparison, but the gap is getting smaller and smaller. The earliest raw materials for the production of honeycomb ceramics were mainly kaolin, talc, aluminum powder, clay, etc., but today a breakthrough has been made, especially in the application of diatomite, zeolite, expansive soil and refractory materials. Honeycomb ceramics are widely used and their performance is getting better and better. good.

In addition to honeycomb ceramics for sintering and molding, non-sintered honeycomb ceramics have also appeared, which greatly improves the activity of catalytic performance. Not only the appearance size has developed from the smallest ball ring shape to large-sized columns, squares and circles. According to different mold designs; it can be made into honeycomb ceramics of different sizes, shapes and structures. For example, the molecular sieve catalyst used in the petrochemical industry for oil refining air adsorption drying has a size of up to 0.8m, a square of 0.25m in width, and the number of holes per square centimeter reaches 25. There have been great changes in raw materials, processes and mechanical manufacturing. In particular, the production process has been greatly improved. Honeycomb ceramics used as catalysts are required not to crack during manufacturing and molding, and the organic components must be released cleanly. In addition to wear resistance, they also require certain mechanical strength and can be recycled and reused many times.

Honeycomb ceramics can be made from a variety of materials. The main materials are: cordierite, mullite, aluminum titanate, activated carbon, silicon carbide, activated alumina, zirconia, silicon nitride, cordierite-mullite, cordierite-aluminum titanate and other composite substrates.

After the activated carbon powder or granules are made into the shape of honeycomb ceramics, the water purification and wastewater treatment capabilities are greatly improved, especially in the pharmaceutical industry for dehydration, decolorization, decolorization and impurity removal of antibiotics, hormones, vitamins, nucleic acid injections and various injections, drugs, etc.

Honeycomb ceramics can be divided into four categories according to their uses: regenerators, fillers, catalyst carriers and filter materials.

The heat capacity of the honeycomb ceramic regenerator is above 1000kJ/kg, and the maximum service temperature of the product is ≥1700°C. It can save fuel by more than 40% and increase the output by more than 15% in furnaces such as heating furnaces, roasters, soaking furnaces, and cracking furnaces. , The exhaust gas temperature is lower than 150°C.

Honeycomb ceramic filler has the advantages of larger specific surface area and better strength than other shape fillers, which can make the vapor-liquid distribution more uniform, reduce bed resistance, better effect, and prolong service life. It is widely used in petrochemical, pharmaceutical and fine chemical industries. It works quite well as a filler.

Honeycomb ceramics have more advantages in catalysts. The honeycomb ceramic material is used as the carrier, and the unique coating material is used. It is made of precious metals, rare earth metals and transition metals, so it has the advantages of high catalytic activity, good thermal stability, long service life, and high strength.

Honeycomb ceramics for catalytic cracking are replacing existing products. Catalytic cracking uses heavy distillate oil between 200-500°C as raw material (including vacuum distillate, straight-run light diesel oil, coker wax oil, etc.), uses aluminosilicate as catalyst, and the reaction temperature is between 450-550°C ( Varies with reactor type). It has a large output (each large-scale catalytic cracking unit cracks more than one million tons of oil per year), and requires high technical conditions (for example, the catalyst needs to be regenerated every few minutes or even seconds when it contacts the oil, and the catalyst that flows through the fluidized bed every minute Up to 10t or more) With the improvement of catalytic activity, in order to accelerate the regeneration speed, more severe regeneration conditions are required. For example, at 600-650°C, or even 700°C, the catalyst consumption is large, 0.3-0.6kg of catalyst per ton of feed oil, and the catalyst with poor mechanical strength consumes much more. This requires a slight increase in catalyst activity, selectivity, and stability, which will be of great significance to actual production. Because of this, honeycomb ceramic catalysts are constantly being introduced, and the market demand is also increasing. These catalysts for catalytic cracking are replaced by honeycomb ceramic catalysts. Honeycomb ceramic catalysts with large size and porous numbers have emerged and have a strong momentum of development.

Honeycomb ceramics have the following advantages as a filter material: good chemical stability, acid and alkali resistance and organic solvent resistance; excellent resistance to rapid heat and rapid cooling, the working temperature can be as high as 1000 ° C; good antibacterial performance, not easy to be degraded by bacteria, not easy to block and easy Regeneration; strong structural stability, narrow pore size distribution, high permeability; non-toxic, especially suitable for food and drug treatment.

It is mainly used in the metallurgical industry. The specific surface area of the honeycomb ceramic body is large, which improves the ability of the filter to absorb and capture small impurities, and has a better filtering effect than traditional porous ceramics, and the molten metal flows smoothly.