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Gas Flow Cell - WIP

Gas Flow Cell - WIP

Gas flow experiments have become a popular in-situ environment for catalysis experiments and can be flexible to fit the needs of the proposed reaction. Flexibility of the system has been established, using Swagelok connections, allowing for the connection of auxiliary equipment before and after the cell. This cell is also compatible with the hot air blower, allowing for the heating of samples. Typically a 1/8" quartz capillary is used with this environment to allow for adaquette gas flow over the sample, allowing for heating up to ~950K. A 1/16" capillary can also be used to allow for higher temperature, but at the expense of reduced gas flow.

A gas delivery system, made up of many MFCs, can also be provided by the beamline to supply:

  • Nitrogen/Argon/Inert Gases

  • <4% H2 in inert gas

  • <10% O2 in inert gas

  • CO2

Due to current extract regulations, we cannot safely extract ammonia, higher percentage hydrogen/oxygen as well as corrosives/alkenes etc. We aim to resolve this as soon as possible. If you are working with water vapour, a trap will need to be provided to avoid extraction of water into the ducts. 

Beyond this, we allow for a lot of flexibility around the cell, and can host user equipment, extra analysis equipment (such as mass spectometers) and much more. Please get in contact to discuss your needs.

High-temperature gas cell experiments

The gas cell can be used in combination with the hot air blower, which can be set to a temperature of RT-950 °C (although the calibrated temperature will be lower and dependent on the size of your capillary).

Experimental considerations

  • Gas flow can cause the sample to move. Glass wool plug? (Recommend <20sccm)

  • No hazardous gases!

  • Make sure the cell is mounted such that the cell holder fits on the beamline

  • Standard capillary sizes: 1/8 and 1/16th inch (Fused quartz)

  • We use self-sealing Swagelok pieces

Suggested data collections

  • Initial 5-minute collection of sample pre-experiment

  • Continuous 15-60 s collections (with frames=[number large enough to cover in situ experiment time])

  • Data can be summed where appropriate post experiment to improve statistics

Temperature:

  • Temperature can be controlled via a run_program command within the collect_pe2_blower scan.

Gas:

  • Gas can be set to discrete ratios and flow rates or can be scripted into a gas program of set gas flows for set time periods.

Example script

robot.dummy_mode = True real_janet.dummy_mode = True run_gas_program = True mfc3_Ar = DisplayEpicsPVClass("mfc3_Ar", "ME08G-EA-GIR-01:MFC3:MASS:FLOW:RD", "SCCM", "%1.2f") mfc3_Ar_setpoint = DisplayEpicsPVClass("mfc3_Ar_setpoint", "ME08G-EA-GIR-01:MFC3:SETPOINT:RD", "SCCM", "%1.2f") mons = ["mfc3_Ar","mfc3_Ar_setpoint"] def set_gas(Ar=5):     #if run_gas_program == True:     print("Setting gas (Ar {} SCCM".format(Ar))     caput("ME08G-EA-GIR-01:MFC3:SETPOINT:WR",Ar) def collect_sample1():     set_gas(Ar=10)     collect_pe2(sf("SAMPLE1",[1,1],"C",1,0.5,”fq3.2"),300,frames=1,monitorsPerPoint=mons,comment='RT')     blower.setTemperature(150)     blower.move_to_beam()     caput("BL15J-EA-BLOW-01:RR",0.16)     pe2.stopBetweenPoints = False     i0.stopBetweenPoints = False     collect_pe2_blower(sf("SAMPLE 1",[1,1],”C",1,0.5,"fq3.2"),60,None,frames=1000, monitorsPerPoint=mons,f2=10,run_program="SetT(150),Hold(1),SetT(340),Hold(60),StopAll()")     blower.off()     blower.move_to_safe()