This README file focuses exclusively on Iso Potential X-ray (IPO-XRD) investigations. The data and files are organized into a folder named Raw_data, an Origin project file (final_IPO_XRD_evaluation.opju), and this README document.

1. Folder Structure in Raw_data:

The Raw_data folder contains the raw data directly obtained from the instrument in '.asc' format and all raw data are additionally provided as .csv for vendor-independent use. The Raww_data folder is divided into three subfolders as follows:

-  CPR_synchrotron_averaged  
This folder contains spatial profile based diffraction patterns obtained from direct CPR measurements. There are a total of 16 files occupying approximately 2.72 MB.

- m_XRD_synchrotron_averaged
This folder includes diffraction patterns from isopotential XRD measurements using the CPR and XRD cell at the synchrotron, recorded at specific positions. The folder contains 16 files totaling approximately 2.72 MB.

- Lab_XRD 
This folder holds diffraction patterns from isopotential XRD measurements using the CPR and XRD cell with a laboratory diffractometer at specific sample positions. The folder contains 12 files with a total size of about 4.4 MB.

2. Scientific background for IPO-XRD measurements:

Iso potential idea can be explained as following: 
-The gas is feeded to CPR using dedicated mass flow controllers. Small amount of reaction mixture at the position of sampling orifice is transferred into a spectroscopic cell containing a tiny amount (few mg) of the same catalyst as inside the reactor, just enough to measure the desired spectroscopic information but as little as possible to minimize conversion in the spectroscopic cell. Once the reaction fluid is separated from the catalyst in the reactor, the chemical composition denoted by a mole fraction vector x is fixed. The pressure drop in the transfer system is kept very small (less than 100 mbar) such that the pressure p in the spectroscopic cell is the same as locally in the reactor. The temperature T of the catalyst in the spectroscopic cell is set to the same value as measured locally in the reactor. In this way, the catalyst in the spectroscopic cell is exposed to the same chemical potential as the catalyst locally in the reactor μ(T, p, x)reactor = μ(T, p, x)spec. cell ⇒ iso potential and should display the same adsorbates, oxidation state and crystalline phases. By scanning the profile reactor from inlet to outlet, the catalyst in the spectroscopic cell goes in good approximation through the same chemical history as the catalyst in the reactor, and spatial profiles of the respective spectroscopic information can be measured.

3. Data Evaluation

Evaluation of the raw data is carried out at Origin Project File: final_IPO_XRD_evaluation.opju. Origin worksheets are additionally provided as  "Final_IPO_XRD_evaluation_all_data_together.csv, Figure4a_CPR_XRD_Synchrotron_Normalized.csv and Figure4b_m_XRD_Synchrotron_Normalized.csv" for vendor-independent use.

The Origin project file (final_IPO_XRD_evaluation.opju) is primarily used to generate Figure 3, 4 and Figures S1 (supplementary file) of the study. 

The following workflow and data processing steps were applied to produce these figures:

-Raw data files were imported into Origin. Each data file comprises two columns: 2θ (two-theta) and intensity. All imported data are compiled into a workbook named all_data_together.

-To enable plotting of all diffraction patterns on a single axis despite differences in X-ray energies used at the synchrotron and in the laboratory, the 2θ values in Column A (CPR Synchrotron), Column J (μ-XRD Synchrotron), and Column S (μ-XRD Laboratory) were converted to the scattering vector Q using the equation:

Q=4πsin(θ)\λ

where λ is the X-ray wavelength used, and θ is the diffraction angle (half of 2θ). 

Creation of Figures:

Figure 3 was created using Origin’s "stacked lines by Y-offsets" plotting function to visualize the diffraction patterns. There is only one X-column (Q values) per dataset since the scattering angle remains constant within each measurement set, while multiple Y-columns represent intensity values. Also, all the specific positions are mentioned in the comments row for each Y-column.
- Figure 3 is consisting three subfigures:
- Figure 3 (a), which is related to CPR synchrotron experiments, is consisting A Column as X-axis and B-I columns as Y axis from "all_data_together" worksheet. Specific CPR positions are given in comments tab
- Figure 3 (b), which is related to m-XRD synchrotron experiments, is consisting J Column as X-axis and L-R columns as Y axis from "all_data_together" worksheet. Specific CPR positions are given in comments tab
- Figure 3 (c), which is related to m-XRD laboratory experiments, is consisting S Column as X-axis and T-Z columns as Y axis from "all_data_together" worksheet. Specific CPR positions are given in comments tab

Figure 4 was produced by normalizing the peak intensities of the MoO3−x reflection at q=1.64 A˚−1 and the MoO2 reflection at q=3.65 A˚−1 relative to specific catalyst positions.
- Worksheet "Figure4a_CPR_XRD_Synchrotron_Normalized" is related to direct synchrotron CPR experiments. CPR positions are shown in column A, peak intensities of the MoO3−x reflection is shown in column B, normalized peak positions are shown in column C. Similarly, peak intensities of the MoO2 reflection is shown in column D, normalized peak positions are shown in column E
- Worksheet "Figure4b_m_XRD_Synchrotron_Normalized" is related to IPO-XRD experiments with the m-xrd cell. CPR positions are shown in column A, peak intensities of the MoO3−x reflection is shown in column B, normalized peak positions are shown in column C. Similarly, peak intensities of the MoO2 reflection is shown in column D, normalized peak positions are shown in column E

Figue S1 (supplementary information) was produced using the worksheet "all_data_together". X-axis (Q values) was related to column S and Y-axis (X-ray intensity) was related to column AA.


4. File Naming Convention:
Example filename: 20251119_CRC1615_B02_Lab_XRD_position_10mm.asc
- YYYYMMDD: Date of creation
- CRC1615: Research project
- B02: Subproject identifier
- Lab_XRD: Measurement method
- position_10mm: Position of the catalyst in the reactor

Number of Records:
XRD_data: 47 files, 12.3 MB in total

5. Access and Licensing Information

Repository and Persistent Identifier:
Published via TORE, DOI: https://doi.org/10.15480/882.15279

License for Use:
- Raw data files (.asc, .opju, .xlsx, .csv): Public Domain Mark (PDM)
- Figures (.png): CC BY 4.0

Access Restrictions:
Open access

Text for Citation:

For raw data (Public Domain):
G. Gizer, H. M. Zeeshan,
"IPO-XRD Data for Oxidative Dehydrogenation of Ethane over MoO3/γ-Al2O3",
Hamburg University of Technology (TUHH), 2026,
DOI: https://doi.org/10.15480/882.15279

For figures (CC BY 4.0):
G. Gizer, H. M. Zeeshan, et al.,
"Iso-Potential Operando X-Ray Diffraction (IPO-XRD) – Figures Illustrating Catalyst Dynamics",
Hamburg University of Technology (TUHH), 2026,
DOI: https://doi.org/10.15480/882.15279

6. Reproducibility and Software Dependencies

Software Required:
- Origin 2025b (.opju files)
- Microsoft Excel or compatible software (.xlsx files)
- Any text editor or spreadsheet software for .csv files
- Image viewer for .png files

Scripts and Workflow:
Data processing scripts are included in .opju files. Analyses can be reproduced using .csv files with standard spreadsheet or analysis software.

Reproducibility Notes:
Key results from the related publication can be reproduced by comparing XRD phase transitions with gas-phase composition data under the reported experimental conditions.

7. Ethical and Legal Aspects
Data Protection:
No personal or sensitive data included; not applicable.

Consent Statement:
Not applicable

8. Versioning and Updates
Version Number:
v1.0

Date of Release:
2026-04-08

Change Log:
Initial release

9. Contact Information
Corresponding Author:
Name: Raimund Horn
Institution: Hamburg University of Technology (TUHH)
Email: horn@tuhh.de
ORCID: 0000-0001-8457-3161
Project Website: https://www.tuhh.de/sfb1615/

