Advantages and features:

1) The vacuum degree in the sample tank can reach 10-3 Pa after the sample treatment begins;

2) Pretreatment, adsorption and desorption of probe molecules can be performed simultaneously or separately in the sample measurement process;

3) The probe molecules needed for measurement are acidic or alkaline molecules, and the high borosilicate glass material can avoid the mutual contamination of various gases;

4) Vacuum treatment system is composed of mechanical pump and glass four-stage diffusion pump in series, which can meet the requirements of high vacuum degree required by sample testing. It has the characteristics of fast pumping speed, small volume, low noise, simple operation and convenient use.

5) The low vacuum part is mainly to remove the high concentration gas or adsorbed residual gas in the system;

6) The door of each part is made of high borosilicate glass, which can meet the requirements of high vacuum, transparent operation and easy debugging;

7) The vacuum measuring instrument uses digital display high precision vacuum gauge;

8) The system is equipped with a permeable quartz infrared absorption pool, which can be used for sample combustion, flow REDOX, extraction and degassment, adsorption reaction and other processing processes, can be moved in or out of the light path of the infrared spectrometer for experiments, the heating temperature of the sample can reach up to 450 degrees;

9) Easy replacement of bellows.

10) High vacuum system and in-situ infrared absorption cell can be changed and customized according to customer requirements.

Product application:

Study on adsorption state and infrared spectroscopy characterization of catalyst

Infrared spectroscopy has been widely used in the study of the surface properties of catalysts. Among them, the most effective and widely used infrared spectroscopy is the study of the "probe molecules" adsorbed on the surface of catalysts, such as: The infrared spectroscopy of NO, CO, CO2, NH3, C3H5N, etc., can provide the information of the "active center" and the species adsorbed on the surface of the catalyst, especially under the condition of in situ reaction. Therefore, it is very important to reveal the catalytic reaction mechanism.

1.1 Study on the adsorption state of CO

Co has a very high infrared extinction coefficient, and its unfilled vacant orbital is easy to interact with the transition metal. At the same time, many important catalytic reactions such as carbonyl synthesis, water gas synthesis, Fischer-Troph synthesis and so on are closely related to Co. Therefore, the study of the adsorption state of Co on the surface of the transition metal is a very extensive research topic.

1.2 Determination of catalyst surface composition

The difference between the surface composition and the bulk composition of the alloy catalyst will lead to the significant difference in the performance of the catalyst. Therefore, the determination of the surface composition of the catalyst is very important to understand the active site of the reaction. The surface composition of bimetallic supported catalysts can be easily determined by means of the competitive adsorption of two gas mixture on the surface of a two-component transition metal catalyst and the determination of their intensity by infrared spectroscopy. A typical example is the infrared spectrum of co-adsorption of Co and NO on a Pt-Ru bimetallic catalyst.

1.3 Geometric and electronic effects

The introduction of the second metal component into the highly dispersed metal catalyst can significantly change the adsorption performance of the catalyst and thus the catalytic activity due to the geometric and electronic effects between the metals. For example, in the Pd-Ag/SiO2 catalyst system, Ag plays a diluent role on Pd. When the Ag content increases, the Pd concentration in double existence decreases, so the bridge Co decreases and the line Co increases, indicating that the geometric effect changes the adsorption performance of Co in the Pd-Ag/SiO2 system. At the same time, with the increase of the Ag content, the red shift of CO adsorption spectrum increases. This indicates that there is an electronic effect between Pd-Ag.

1.4 Study on adsorption molecular interaction

CO adsorption on transition metal surface are d - PI feedback, nco with d - how PI feedback are related, and degree of d - PI feedback about d orbitals of the metal itself, as a result, the CO adsorption state of infrared absorption spectrum of chemical shift, can lead to other molecules and CO adsorption together between molecules and metal components of the electron transfer process. For example, when the Lewis base that can give electrons is co-adsorbed on Pt with CO, according to the D-π feedback principle, the CO stretching vibration adsorbed on Pt moves to the low wave digit, and when the acceptor that can accept electrons is co-adsorbed on Pt with CO, according to the D-π feedback principle, the CO stretching vibration adsorbed on Pt moves to the high wave digit.

Characterization of oxides and zeolite catalysts by infrared spectroscopy

2.1 Determination of solid surface acidity

The acid site on the solid surface can generally be regarded as the active site on the oxide catalyst surface. In many catalytic reactions such as catalytic cracking, isomerization and polymerization, hydrocarbon molecules interact with surface acid sites to form carbocation, which is the intermediate species of the reaction. The theory of positive carbon ion can successfully explain the reaction of hydrocarbon on acid surface and also provide a strong proof for the existence of acid potential.

To characterize the properties of solid acid catalysts, it is necessary to determine the type of surface acid sites (Lewis acid, Bronsted acid), the strength, and the amount of acid. There are many methods for the determination of surface acidity, such as alkali titration, alkaline gas adsorption method, thermal difference method, etc., but these methods can not distinguish L-acid and B-acid parts. Infrared spectroscopy is widely used to study the surface acidity of solid catalysts, which can effectively distinguish L-acid from B-acid. In this method, basic adsorbents such as ammonia, pyridine, trimethylamine and n-butylamine are commonly used to characterize the acid sites, among which pyridine and ammonia are widely used.

2.2 Study on hydroxyl groups on the surface of oxides

The surface structure hydroxyl of oxides, especially those with large surface ratio, is related to many catalytic reactions, such as dehydration reaction and formic acid decomposition reaction, and the properties of the surface structure hydroxyl are closely related to surface acidity. For many years, people have conducted a lot of research on the surface hydroxyl of oxides. Most of the studies focus on the structure and properties of the hydroxyl groups on the oxide surface and the relationship with the acid center, which is related to the reaction performance of the catalyst. There are many methods to study the hydroxyl group on the surface of catalyst, but the most effective method is infrared spectroscopy.

2.3 Studies on oxygen species on oxide surface

Methane is a simple, symmetric and chemically inert molecule of hydrocarbon molecules. It is of great academic significance to understand the activation mechanism of low carbon hydrocarbons represented by methane from the perspective of basic research. However, methane molecules are difficult to adsorb on the catalyst surface, so it is difficult to directly observe its activation on the oxide surface. However, it is very difficult to study the oxygen species on the oxide surface (especially the basic oxide surface) because of the existence of a layer of stable carbonate on the surface. For the above reasons, the study of oxygen species on oxide surface has not made great progress. In recent years, "chemical capture" technique, isotope exchange technique and low-temperature in-situ infrared spectroscopy have been used to obtain some important information about surface oxygen species and methane activation.

Study on the application of in-situ infrared spectroscopy to reaction mechanism

The adsorbed states of various molecules on the surface of catalysts have been studied for a long time and a lot of important information has been obtained, but these information is measured when the reaction does not take place. Type of adsorbed species and reaction conditions, structure, properties and adsorption under the condition of species type, structure, performance, has the very big difference, therefore, only using adsorption were measured under the condition of information cannot be accurately clarify the reaction mechanism of adsorbed species, therefore, under the condition of reaction adsorption species studied is necessary. However, under the reaction conditions, not all species adsorbed on the surface of the catalyst participate in the reaction, so how to identify the "intermediate species" involved in the reaction among a variety of adsorbed species is a very important topic. In situ infrared spectroscopy can measure the dynamic behavior of the species adsorbed on the catalyst in the reaction state, so the dynamic information of the species on the catalyst surface can be obtained and the reaction mechanism can be inferred accordingly.

Detailed introduction:

The in-situ infrared spectroscopy characterization high vacuum system is a special equipment used to determine the surface composition, adsorption, acidity, species, surface hydroxyl group and reaction mechanism of the catalyst, including the high vacuum system and the in-situ infrared absorption cell. The chemical adsorption determination of ammonia, pyridine, carbon monoxide, nitric oxide, methanol, ethanol and other compounds and the study of reaction mechanism can be carried out with Bruker Brook and other major infrared spectrometers.

Catalyst characterization is essential for understanding changes in the structure and composition of catalysts during pretreatment, induction and reaction conditions, and during regeneration. Knowledge of catalytic reaction mechanisms, in particular the structure, dynamics and energetics of the reaction intermediates generated along the catalytic reaction pathway, can provide a deeper understanding of the development of new catalysts and the improvement of existing catalysts. In situ spectroscopic observation is also the most effective technique to elucidate the reaction mechanism, the dynamics of the interaction between molecules and catalysts, and the structure of intermediates. These studies can also provide information on the thermodynamic aspects of catalyst - substrate interactions and activation barriers. The study of reaction mechanism and kinetics, especially the in-situ observation of catalytic intermediates, is very necessary for the development of catalytic science. Such results provide a comprehensive knowledge of catalysis and help to clarify the relationship between catalyst structure and function.