How to accurately categorize catalysts
What is a catalyst?
According to the 1981 definition of the International Union of Pure and Applied Chemistry (IUPAC), a catalyst is a substance that changes the rate of a reaction without changing the total standard Gibbs free energy of the reaction.
Catalysts were first discovered by the Swedish chemist Betserius, who first introduced the concepts of “catalysis” and “catalyst” for use in chemical reactions in a paper published in the journal Annals of Physics and Chemistry as early as 1836.
The action caused by a catalyst in a chemical reaction is called catalysis. Solid catalysts are also called catalysts in industry.
How are catalysts categorized?
There are many types of catalysts:
–By state, they can be classified into liquid catalysts and solid catalysts.
–According to the phase state of the reaction system, they are divided into homogeneous catalysts and multiphase catalysts. Homogeneous catalysts include acid, base, soluble transition metal compounds and peroxide catalysts; multiphase catalysts include solid acid catalysts, organic base catalysts, metal catalysts, metal oxide catalysts, complex catalysts, rare earth catalysts, molecular sieves catalysts, biocatalysts, nanocatalysts, etc.
–According to the type of reaction, there are polymerization, polycondensation, esterification, acetalization, hydrogenation, dehydrogenation, oxidation, reduction, alkylation, isomerization and other catalysts.
–According to the magnitude of action, there are also main catalysts and co-catalysts.
What are the uses of catalysts?
Catalysts have an important and wide range of applications in chemical production, and are used in the production of fertilizers, pesticides, and a variety of chemical raw materials.
Catalysts are widely used in various industries around the world, and there are great prospects for the future development of catalysts in the research of scientific theories, the development and utilization of clean energy, environmental protection and improvement of economic efficiency, as well as the governance and protection of the human living environment. In short, catalysts and their development are indispensable for the survival and development of human beings, for food, clothing, housing and transportation.
Catalysts｜What are the categorization rules?
According to the “Import and Export Tariff Rules of the People’s Republic of China (2020)” and “Notes on Commodities and Items under the Import and Export Tariff Rules (2017)”, catalysts under item 38.15 include preparations that cause or promote certain chemical reactions, and products that prevent chemical reactions are not categorized under this item.
It is mainly divided into the following two categories:
(i) Those consisting primarily of one or more active substances deposited on a carrier (called “carrier catalysts”) or a mixture of active substances as a base. In most cases, these active substances are certain metals, metal oxides, other metal compounds and mixtures thereof. Metals often used alone or in compound form are cobalt, nickel, palladium, platinum, molybdenum, chromium, copper or zinc. The carrier (which may sometimes be activated) is usually composed of vanadinite, carbon, silica gel, silica fossil powder, or ceramic material. Carrier catalysts include Ziegler catalysts and Ziegler-Natta type catalysts.
(ii) are mixtures of certain compounds as basic ingredients which vary in nature and proportion according to the different catalytic chemical reactions. These agents include:
Free radical “catalysts” (e.g., organic solutions of organic peroxides or azo compounds, redox mixtures);
Ionic “catalysts” (e.g., alkyl lithium catalysts);
“Condensation reaction catalysts” (e.g. mixtures of calcium acetate and antimony trioxide).
Not included in heading 38.15:
Spent catalysts used for the extraction of base metals or the preparation of base metal compounds and spent catalysts used primarily for the recovery of precious metals;
Separate compounds for which chemical definitions already exist;
Catalysts of pure metals or alloys of pure metals in the form of fine powders or screen fabrics, etc;
Formulated rubber accelerators for rubber vulcanization.
Catalysts｜What are the precautions for import declaration?
