chemical composition of the catalyst
1. Chemical composition
Unactivated fertilizer catalysts are mostly complex mixtures of metal oxides (or sulfides/salts, etc.). The chemical composition of general injection is a colloquial expression of general chemical analysis, not the actual structure of the catalyst. For example, in the chemical composition of A110 series ammonia synthesis catalysts, Al2O3 and CaO form solid solution with Fe3O4, and the listed Al2O32 ~ 3% only means that the weight ratio of Al3 in the oxidized state catalyst after conversion to Al2O3 is equivalent to 2 ~ 3%.
2. Main catalyst/auxiliary catalyst
Fertilizer catalysts are all multi-component catalysts, one of which plays a major role in the catalytic reaction in the catalytic process, called the main catalyst.
In order to improve any other properties of the catalyst, the team called co-catalysts, which are generally divided into two types: denatured co-catalysts and structural co-catalysts.
In the production process of sulfuric acid, the alkali metal sulfate in the vanadium catalyst has no direct catalytic effect, but it forms a new compound with the vanadium oxide after addition, and the activity of the vanadium catalyst increases by dozens of times, which is called a denatured catalyst.
The ZnO in the low side has no activity itself, nor can it improve the activity of the surface of the copper crystal unit, but its fine particles are distributed among the copper particles, which stabilize the surface of the copper crystal and prolong the life of the catalyst. ZnO is called a structural auxiliary catalyst. .
Heterogeneous catalytic reactions take place on the catalytic surface, and in order to increase the effective surface area, porous objects are often used to load active components, and this porous object is called a carrier, which is called a carrier.
Binders are added in the catalyst production process to improve the mechanical strength of the catalyst.
In the catalyst molding process, in order to reduce the friction between the material and the mold and between the materials, graphite and other inert substances with lubricating effect are added.
6. Add substances to improve the pore structure in the catalyst production process, and the crude extractant usually loses gas during the activation process. Sulfuric acid powder/stearate/carboxymethylcellulose/nitrate, etc.
Catalytic Misunderstanding Analysis
Regarding use, here we want to help students organize:
1. Not all reactions to a particular reaction. Like hydrogen peroxide? We used manganese dioxide as a catalyst in the experiment to produce oxygen from potassium chlorate, but this is not to say that manganese dioxide is the catalyst for all reactions. That's just the catalyst for this reaction, which needs to be clearly understood by everyone.
2. Different catalysts can be used for the same reaction. This is not set in stone. Therefore, when it comes to making oxygen from hydrogen peroxide, there are solutions to various reaction rates, such as using copper sulfate or iron oxide.
Can be reused. After the reaction is completed, the catalyst can be dried and kept for the next use to obtain the reuse effect and avoid waste.