What is chemical adsorption? Thermal catalytic in-situ characterization method

Chemical adsorption is the process of electron transfer, exchange, or share between adsorbate molecules and solid surface atoms (molecules), forming chemical bonds.It has important applications in catalysis, corrosion, electrolysis, metal and metallurgy.The characteristics of chemical adsorption: only single-layer adsorption occurs; The heat of adsorption is equivalent to the heat of chemical reaction; Selective; Many are irreversible, etc.According to whether activation energy is required, it can be divided into activated adsorption and non activated adsorption, with the former having a slower rate than the latter.

There are three mechanisms of chemical adsorption: gas molecules lose electrons and become positive ions, which are adsorbed on the negatively charged solid surface where electrons are obtained; Solids lose positive electrons and adsorb negatively charged gases; Gas and solid share electrons to form covalent or coordination bonds.

Chemical adsorption analyzer is one of the most commonly used methods for in-situ characterization of thermal catalysis, which is developed based on temperature programmed technology, The PCA-1200 series chemical adsorption instrument can be used for gas-phase components such as carbon oxides (COx), nitrogen oxides (NxOx), ammonia (NH3), hydrogen (H2), oxygen (O2), nitrogen (N2), etc., to achieve temperature programmed reduction (TPR), temperature programmed desorption (TPD), temperature programmed oxidation (TPO), temperature programmed sulfurization (TPS), temperature programmed surface reaction (TPSR), and chemical pulse titration experiments, evaluating the reaction mechanism, activity, selectivity, synergistic effect, stability, and toxicity resistance of the catalyst. Meanwhile, the chemical adsorption instrument can add a photothermal system to meet the common characterization under both light and thermal conditions.