Reaction temperature serves as a core reference for catalyst selection, exerting a notable impact on catalytic activity, structural stability and service life. Different catalyst systems feature distinct active temperature ranges and heat resistance. Selecting catalysts properly according to actual operating conditions can well meet reaction requirements, lower the risk of catalyst deactivation, and improve the cost efficiency and operational stability of the whole system.
For low-temperature operations below 200℃, precious metal catalysts, manganese-based or copper-based composite oxide catalysts are recommended. These catalysts deliver satisfactory activity at low temperatures, and are widely used in low-temperature desulfurization, low-temperature denitrification and catalytic degradation of low-concentration VOCs. Generally, they have limited heat resistance, and their activity may decline sharply once the temperature rises significantly. During operation, sudden temperature changes should be avoided. Raw materials also need pretreatment to prevent contaminants such as oil and dust from covering active sites, so as to slow down the deterioration of catalytic performance.
The range of 200℃ to 350℃ is the optimal active temperature zone for most industrial catalysts. Cobalt-molybdenum and nickel-molybdenum hydrogenation catalysts, alumina-based hydrolysis catalysts and vanadium-based catalysts work well in this temperature range. They are commonly applied to oil hydrofining, sulfur recovery, organic sulfur hydrolysis and medium-temperature flue gas treatment. Hydrogenation catalysts normally require pre-sulfurization to achieve desirable catalytic activity. Frequent temperature fluctuations may lead to carrier pulverization and loss of active components, so a steady temperature environment is recommended for routine operation.
Operations between 350℃ and 500℃ set higher requirements for catalyst thermal stability. Nickel-based catalysts, iron-based catalysts and modified high-temperature resistant molecular sieves are suitable for hydrocracking, coal gas purification and high-temperature organic sulfur conversion. When choosing products, priority can be given to the thermal stability of catalyst carriers. Reasonable control of system oxygen content helps mitigate deactivation caused by carbon deposition and sintering under high temperatures.
For operating temperatures above 500℃, heat-resistant catalysts including iron-chromium series, rare earth composite oxides and perovskite-type materials are preferred. Controlling the heating rate during operation can reduce structural damage from thermal shock and ensure long-term and stable catalytic performance.