Traditional chemical reactions mainly activate reactants through heating, providing the energy needed to overcome thermodynamic barriers and promote the transformation of reactants into products. In a thermocatalytic system, reactant molecules are adsorbed and activated on the surface of the catalyst, altering the chemical reaction pathway to reduce the activation energy and facilitate the reaction. In contrast, photocatalysis uses photon energy to catalyze reactions. Its mechanism and pathway differ fundamentally from thermocatalysis, offering mild reaction conditions and ease of operation.
In recent years, with the gradual advancement of catalysis research, scientists have discovered that photothermal synergistic catalysis can not only enhance catalytic efficiency but also convert low-density solar energy into high-density chemical energy. The effective combination of the two surpasses the effects achievable by thermocatalysis or photocatalysis alone. By adjusting reaction conditions, it is possible to regulate reaction activity and selectivity, offering immeasurable value in the energy and environmental fields. This has become the focus of current research on novel catalytic technologies.
However, in traditional tubular furnace thermocatalytic reactors, the catalyst is packed at the core of the furnace. Light is introduced through side openings in the furnace wall, resulting in three main reaction modes:
Figure 1. Three reaction modes
Although these modes achieve photothermal synergistic catalysis, the side openings disrupt the heating structure of the furnace, causing uneven heating of the catalyst. To minimize heat loss, the diameter of the light window is usually 1–2 cm, far smaller than the 50 cm diameter of the light spot from the light source. This low light utilization efficiency impacts the effectiveness of photothermal synergistic catalysis.
There are four main ways to improve the utilization efficiency of light energy from the light source in such devices:
Two strategies to increase light energy input:
① Increase the light source power;
② Enlarge the light-receiving area of the device.
The PLS-SME300E H1 Xenon Light Source features an innovative light-enhancing guiding structure that minimizes light transmission loss while focusing most of the output energy into the central area of the light spot. Paired with the PLR-RP Series Photothermal Catalytic Reaction Evaluation Device, the light window diameter has been increased from the traditional 1 cm to 3 cm, enhancing the light-receiving area by 9 times compared to conventional designs. This allows for efficient light transmission and maximized utilization without altering the traditional thermocatalytic reactor structure.
Figure 2. (a) PLS-SME300E H1 Xenon Light Source; (b) Schematic of the light-enhancing guiding structure inside the PLS-SME300E H1 Xenon Light Source.
To preserve the structural integrity of traditional thermocatalytic reactors and maintain temperature uniformity and stability, the PLR-RP Series Photothermal Catalytic Reaction Evaluation Device adopts a new top-opening structure instead of the conventional side-opening design. Light is introduced from the top of the reaction device. To prevent photon loss caused by long light paths from the top opening, a quartz light guide rod has been added to enhance light conduction efficiency. The introduction of this quartz structure significantly improves light transmission efficiency, achieving a measured efficiency of up to 82%, outperforming reactors with shorter light paths but side openings. (For inquiries, call: 400-1161-365)
Figure 3. (a) Traditional side-illumination; (b) Innovative top-illumination.
Since solid catalysts have poor light transmission, thick catalyst layers prevent photons from reaching the lower layers, reducing photon absorption efficiency. The PLR-RP Series Photothermal Catalytic Reaction Evaluation Device employs an innovative top-illumination design with two optional emission modes: planar illumination and ring illumination.
If a planar reactor is selected, the recommended maximum catalyst layer thickness is 3 mm, with a maximum catalyst load of 0.9 mL. Compared to oblique or side-illumination modes, planar illumination provides a larger catalyst light-receiving area, better light uniformity, and supports a mode where reactants penetrate the catalyst. This optimizes both photon absorption and substrate adsorption efficiency, making it suitable for small-scale experiments.
For catalyst loads exceeding 0.9 mL, a ring-illumination reactor can be selected. This design includes a specially designed side-emitting quartz light rod, which ensures the catalyst layer thickness remains ≤3 mm while increasing the maximum catalyst load to 9 mL. The catalyst light-receiving area can be expanded from 0.3 cm² in planar mode to approximately 20 cm², representing a nearly 70-fold increase. This greatly enhances photon utilization efficiency.
The ring-illumination reactor not only improves light utilization efficiency but also significantly boosts substrate adsorption and conversion rates, making it ideal for scale-up production.
Figure 4. Unique innovative ring-illumination reactor in the PLR-RP Series Photothermal Catalytic Reaction Evaluation Device.
