The photocatalytic CO₂ reduction reaction is typically categorized into gas phase and liquid phase based on the phase of the reaction system.
In liquid phase photocatalytic CO₂ reduction, solid photocatalysts are evenly dispersed in a solution and stirred using a magnetic stirrer to precipitate the photocatalyst and enhance dispersion, forming a suspension. However, the limited solubility of CO₂ in the solution and the significant impact of solution pH on solubility restrict the development of the liquid phase photocatalytic CO₂ reduction reaction.
In gas phase photocatalytic CO₂ reduction, photocatalysts are placed on a platform inside the reactor, and CO₂ gas can fill the entire reactor and reaction system. In the gas phase, the diffusion coefficient of CO₂ gas is four orders of magnitude higher than in a liquid, allowing CO₂ gas to participate in the photocatalytic reaction. It also makes it easier for gaseous products to desorb. Moreover, compared to the liquid phase photocatalytic CO₂ reduction reaction, the gas phase offers cost advantages as it avoids the separation of photocatalysts, making it more suitable for industrial applications.
For more details, refer to "Influence of Reactant Phase on Conversion in Photocatalytic CO₂ Reduction".
1. Efficient Circulation: The magnetic drive piston pump ensures gas mixing time <10 minutes over a wide pressure range, preventing concentration gradients and ensuring accurate product detection.
2. High Mass Transfer Efficiency: The gas-solid phase reactor employs a gas "penetration" scheme, allowing CO₂ to come into full contact with the photocatalyst, enhancing mass transfer efficiency and promoting photocatalytic CO₂ reduction.
3. Fully Automatic Online Analysis: Effectively eliminates human error in operation, liberating manpower and ensuring more precise reaction durations.
4. Stable Light Intensity: Effectively avoids experimental errors caused by natural light intensity decay.
Labsolar-6A All-Glass Automatic Online Trace Gas Analysis System is a comprehensive system that includes sample pretreatment unit, reaction unit, gas circulation unit, automatic sampling and injection unit integrated into one reaction system.
1. Full Penetration Reactor to Improve Gas-Solid Phase Mass Transfer Efficiency
Currently, gas-phase reactions in photocatalytic CO₂ reduction are mainly divided into two methods. One is to coat photocatalysts on a substrate, forming a thin film, and CO₂ with a certain humidity flows over the top layer of the film, known as the thin-film gas-solid phase reaction mode, as shown in Figure 1 (a). The other is the direct passage of CO₂ with a certain humidity through the photocatalyst bed, known as the fixed bed gas-solid phase reaction mode, as shown in Figure 1 (b).
The thin-film gas-solid phase reaction mode mainly relies on the passive diffusion of CO₂, but with the increase in reactor thickness, the probability of collision between CO₂ and photocatalyst gradually decreases, limiting mass transfer efficiency.
Unlike passive diffusion, the fixed bed gas-solid phase reaction mode uses a gas "penetration" reactor in combination with the magnetic drive piston pump in the Labsolar-6A All-Glass Automatic Online Trace Gas Analysis System, allowing CO₂ gas to fully contact the photocatalyst, improving mass transfer efficiency, and thus increasing the reaction conversion rate. In experiments, it only requires the introduction of CO₂ with a certain humidity into the reaction system.
2. Low Adsorption, High Circulation Efficiency Glass System to Ensure Sample Repetition and Linearity.
Unlike the negative pressure system for water photolysis, photocatalytic CO₂ reduction experiments are generally conducted under atmospheric pressure or slight negative pressure conditions with high concentration of raw gases. CO₂ is a recombined gas, and relying solely on the free diffusion of gases cannot quickly achieve gas mixing, making gas circulation particularly important for accurate testing in photocatalytic CO₂ reduction experiments. The Labsolar-6A All-Glass Automatic Online Trace Gas Analysis System uses a sealed circulation pipeline system, with CO₂, CO, CH₄, H₂, O₂, C₂H₄, etc., continuously flowing in a single direction under the drive of the magnetic drive piston pump. The magnetic drive piston pump is compatible with a wide range of gas circulation pressures, providing powerful gas circulation with fast gas flow rates. The system's circulation pipeline has a small volume, enabling rapid mixing of gases such as CO₂, CO, CH₄, H₂, O₂, C₂H₄, avoiding errors caused by concentration gradients in the experimental results.
The main material of the Labsolar-6A All-Glass Automatic Online Trace Gas Analysis System is high borosilicate glass, known for its high chemical inertness and low gas resistance. When conducting photocatalytic CO₂ reduction experiments, it doesn't adsorb any gases, accurately reflecting the intrinsic activity of the catalyst.
3. Carefully Designed Sealing Structure
4. Fully Automatic Sampling and Injection System, Liberating Manpower and Improving Experimental Efficiency
The Labsolar-6A All-Glass Automatic Online Trace Gas Analysis System is a fully automatic online analysis system with simple operation, saving time. All parameter settings can be completed on the system's built-in 4.5-inch TFF color touch screen. The color touch screen can display real-time internal parameters such as reaction pressure and ambient temperature. The instrument has built-in experimental methods to control the action of glass valves, gas chromatograph, and vacuum pump.
The automatic sampling and injection unit of the Labsolar-6A All-Glass Automatic Online Trace Gas Analysis System, controlled by software programs, rotates the glass valve using a robotic arm to achieve fully automatic sampling and injection. With a "one-click" trigger, it eliminates complex operations, saves research time, and prevents human errors. In combination with the Microsolar 300 xenon lamp light source, it can achieve long-term experiments without human intervention, making it especially suitable for long-term experiments in photocatalytic CO₂ reduction.
5. Temperature Control Structure
The Labsolar-6A All-Glass Automatic Online Trace Gas Analysis System uses a serpentine condenser to reduce the entry of low-boiling-point components such as water vapor, acetonitrile, and triethanolamine into the circulation pipeline during photocatalytic CO₂ experiments, protecting the gas chromatograph. An optional cold trap can further separate low-boiling-point components, extending the service life of the vacuum pump.
6. Protective Cover
The all-glass automatic online trace gas analysis system has a metal protective casing that provides a certain level of protection against possible gas leaks due to radiation. An anti-light cover can be optionally added to effectively prevent light pollution.
| Gas Circulation Parameters | |
| Gas Mixing Time | H₂, O₂, CH₄, CO Mixing Time <10 min |
| Standard Curve Linearity | R² > 0.9995 when H₂ content is in the range of 100 µL to 10 mL |
| Repeatability | RSD < 3% for four consecutive samples at the same concentration |
| Passive Magnetic Drive Piston Pump | Displacement of 6 mL per stroke, provides excellent circulation driving force from vacuum to atmospheric pressure |
| No electrical connections in the tubing, no risk of hydrogen explosion, and no interference from electrolysis water | |
| Features a one-way valve structure for one-way circulation in all tubing | |
| Sampling Method | Quantitative loop located in the multi-way glass sampling valve, non-chromatographic sampling |
| Circulation Tubing | The narrowest tubing has an inner diameter of 3 mm, non-small-caliber chromatographic tubing, low gas resistance |
| Appearance and Structural Parameters | |
| Reactor | Adaptable for photocatalytic, photoelectrocatalytic, and photothermal reactors |
| Customizable according to actual experimental requirements | |
| Overall Dimensions (mm) | 490(L) × 520(W) × 740(H) |
| Metal Protective Enclosure | Provides some protection against potential gas leaks due to radiation |
| Light Shield | Portable light shield for effective light pollution prevention |
| System Tubing Parameters | ||||
| Absolute Vacuum Level | ≤1.5 kPa | Pressure Range | 0 kPa ~ Atmospheric Pressure | |
| Number of Valves | 7 | Tubing Volume | 65 mL, strong system enrichment capacity | |
| Tubing Material | High borosilicate glass, highly chemically inert, no adsorption | |||
| Valve Process | High borosilicate glass material, valve plug and valve seat using precision grinding process | |||
| Vacuum Grease | Imported Dow Corning vacuum grease, resistant to chemical corrosion, low vapor pressure, low volatility, operating temperature: -40 ~ 200°C | |||
| Quantitative Loop | 0.6 mL, 2 mL optional, adjustable system sensitivity | |||
| Gas Cylinder | 150 mL, suitable for system expansion and storage of reaction gases such as CO₂ | |||
| Tubing Temperature Control | Both circulation and sampling tubing can be temperature-controlled, up to 200°C | |||
| 10-stage program temperature control, temperature control accuracy ±0.1°C | ||||
| Condenser | Spherical | Adequate condensation, prevents water vapor from entering the gas chromatograph and vacuum pump | ||
| Serpentine | ||||
| Trap (optional) | Separates low-boiling-point components, extends the life of the vacuum pump, and improves system vacuum | |||
| Control Unit Parameters | |
| Software Module | 32-bit control software and 4.5-inch TFF color touch screen, real-time display of internal system parameters such as reaction pressure and ambient temperature |
| Built-in instrument methods for controlling glass valve actions, gas chromatograph, and vacuum pump startup and shutdown, easy operation | |
| In automatic control mode, it can display valve positions in real-time and has safety protection and warning functions Sensors automatically prompt for vacuum grease replacement |
|
| Has a secondary encrypted debugging program for equipment debugging, internal method setting, and flexible use by experienced users | |
| Automatic Sampling Valve | High borosil icate glass material with built-in quantitative loop |
| Multi-way composite sampling valve, reduces system circulation volume | |
| Supports manual, automatic, and semi-automatic operation modes | |
| Vacuum Pump | Pumping rate: 6 L/s |
| System control software automatically controls startup and shutdown, intermittent operation, low noise | |
| Includes a one-way solenoid valve to prevent oil reverse flow | |
| Detection Parameters | |
| Detection Range | Various trace gases including H₂, O₂, CH₄, CO |
| Detection Limit /μmol | H₂: 0.05; O₂: 0.1; CH₄/CO: 0.0005 |
| Gas-phase CO₂ Reduction Reaction System and Related Equipment | Main Functions |
| Labsolar-6A All-Glass Automatic Online Trace Gas Analysis System | Reaction unit, fully automatic sampling and injection unit |
| Gas Chromatograph | Qualitative and quantitative analysis of CO, CH₄, H₂, O₂, C2H₄, CH₃OH, and other products produced in the reaction |
| Ion Chromatograph/High-Performance Liquid Chromatograph | Qualitative and quantitative analysis of HCOOH produced in the reaction |
| Low-Temperature Constant Temperature Bath | Controls the temperature of the reaction solution |
*The Labsolar-6A All-Glass Automatic Online Trace Gas Analysis System can be used in conjunction with most models of gas chromatographs, with detection limits for H₂, O₂, CH₄, CO being 0.05 µmol, 0.1 µmol, 0.0005 µmol, and 0.0005 µmol, respectively. This allows for the evaluation of the activity of catalysts with different yields. It features a mature chromatographic configuration solution for one-stop qualitative and quantitative analysis of the main gas-phase products and some liquid-phase products of gas-phase photocatalytic CO₂ reduction reactions.
| Institution | Published Journal | References |
| Kunming University of Science and Technology | Advanced Energy Materials | [5] |
| Hunan University | Catalysis Science Technology | [6] |
| Zhejiang Normal University | Angewandte Chemie International Edition | [7] |
| Three Gorges University | ACS Catalysis | [8] |
| Nanjing University of Aeronautics and Astronautics | Chemical Engineering Journal | [9] |
