Applying mass flow for novel process of CO2 hydrogenation

CO2 hydrogenation  

As hydrogen continues to increase in popularity as a fuel, demand for methanol and ethanol are also expected to increase. These chemicals are often made using a process called CO₂ hydrogenation which reduces CO₂ to CO and H₂O via a thermodynamically intensive process called the reverse water gas shift reaction (RWGSR).  

CO2 hydrogenation using renewable hydrogen, such as sourced from green, gold, orange, or white hydrogen, is a clean process that allows for CO₂ to be made into a series of different end-products, including methanol, formic acid, and ethanol while simultaneously reducing CO₂ emissions. By using CO₂ hydrogenation and green hydrogen to make hydrogen carriers such as methanol, the hydrogen industry can more easily store hydrogen gas by converting it to chemicals that are easier to transport. 

Although this process normally requires high temperatures and pressures, researchers at the Tata Institute of Fundamental Research (TIFR) located in Mumbai have developed a method for CO₂ hydrogenation at room temperature by plasmonic excitation of H₂ and CO₂ via plasmonic catalysts.  

In their process, the researchers at TIFR convert CO₂ to CO at selectivity greater than 95% by applying the phenomenon of localized surface plasmonic resonance (LSPR) that explains how electrons at the surface of metals oscillate as their frequency matches that of incident electromagnetic radiation. In other words, these researchers use special gold-nickel (Au-Ni) nanoparticle catalysts to reduce CO₂ to CO in the presence of solar light and H₂ within a light reactor. As a result, much less energy is required to overcome the activation barrier, thus reducing the overall energy required to make different end products via CO₂ hydrogenation. 

Designing the new process 

In the experimental design, CO₂ and H₂ are mixed into a continuous-flow reactor such that the Au-Ni catalyst bed is kept at about 1 mm in order to allow for sufficient light penetration. The intensity of the light and temperature are adjusted in order to optimize the efficiency under different operating conditions. However, the flow of CO₂ and H₂ are kept constant at 10 mL/min and 1 mL/min in order to create stable gas conditions in the reactor. 

Using mass flow for stable research flow conditions in CO2 hydrogenation  

Because the experimental CO₂ hydrogenation processes requires stable flow conditions for CO₂ and H₂ in order to test other operating conditions, highly repeatable, precise, and accurate low flow full-scale control is required. Alicat MC-Series and CODA KC-Series mass flow controllers provide near-instantaneous, reliable, repeatable low flow control at full-scales down to just 0.5 SCCM or 40 g/hr.  

Communication for automated control using either a PLC or computer via analog, serial, or industrial protocols allow for highly personalized flow data measurement and control. Features such as batching and totalizing allow for the tracking of flow data.  

Alicat MC-Series: 

• Full-scale ranges of 0.5 SCCM to 5,000 SLPM 
• Control range of 0.01% – 100% of full-scale 
• Accuracy up to ±0.5% of reading or ±0.1% of full-scale, whichever is greater 
• Repeatability up to ±0.1% of reading and 0.02% of full-scale 
• Response times less than 30 ms 

 CODA KC-Series: 

• Full scale ranges from 40 g/h to 100 kg/h  
• Control range from 2% – 100% of full-scale 
• Gas accuracy up to ±0.5% of reading or ±0.05% of full-scale, whichever is greater 
• Repeatability up to ±0.05% of reading and ±0.025% of full-scale 
• Pressure rated up to 4000 PSIA at higher full-scales

Alicat’s devices are widely used within various industries such as vacuum applications, coating, oil and gas, hydrogen, leak testing, and many research applications. In total, Alicat devices have been cited in over 1,000 peer-reviewed papers and are widely used within industries such as aerospace, glass manufacturing, chromatography and spectroscopy, chemical vapor deposition, and bioreactor manufacturing.