In situ synchrotron‐based X‐ray powder diffraction and micro‐Raman study of biomass and residue model compounds at hydrothermal conditions
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2015-03-11 |
| Journal | Energy Science & Engineering |
| Authors | Morgan L. Thomas, Ian S. Butler, Janusz A. Koziński |
| Institutions | Keele University, University of Saskatchewan |
| Citations | 3 |
| Analysis | Full AI Review Included |
In Situ Synchrotron/Raman Analysis of Biomass in Hydrothermal Diamond-Anvil Cells (HDAC)
Section titled “In Situ Synchrotron/Raman Analysis of Biomass in Hydrothermal Diamond-Anvil Cells (HDAC)”Executive Summary
Section titled “Executive Summary”This technical analysis highlights the critical role of high-purity Single Crystal Diamond (SCD) in enabling in situ time-resolved analysis of complex chemical processes under extreme hydrothermal conditions, specifically supercritical water (SCW).
- Application Focus: Utilizing the Hydrothermal Diamond-Anvil Cell (HDAC) to analyze the dissolution and transformation kinetics of biomass models (cellulose, calcium oxalate) under SCW conditions.
- Methodology: Successful integration of two complex techniques—Synchrotron X-ray Powder Diffraction (XRPD) and Laser Micro-Raman Spectroscopy—requiring pristine optical and mechanical diamond windows.
- Extreme Conditions: Experiments reached temperatures up to 425 °C, achieving conditions well into the supercritical phase of water (Tc = 374 °C).
- Key Finding: Irreversible loss of cellulose crystallinity was observed sharply above 225 °C via both XRPD and Raman signals, enabling definition of kinetic boundaries.
- Diamond Necessity: The successful acquisition of reliable XRPD and Raman data is fundamentally dependent on the low scattering, high transparency, and mechanical integrity provided exclusively by high-quality SCD anvils.
- 6CCVD Advantage: 6CCVD provides the necessary Optical Grade SCD material, optimized for transparency across X-ray and broad spectroscopic ranges, essential for replicating and advancing this high-end research.
Technical Specifications
Section titled “Technical Specifications”The following table extracts the hard data points related to the experimental conditions achieved using the SCD-based HDAC setup.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Temperature Achieved | 425 | °C | For XRPD measurements of materials in SCW |
| Critical Temperature (Water) | 374 | °C | Defines supercritical region (SCW) |
| Cellulose Crystallinity Loss Onset | > 225 | °C | Point of irreversible dissolution/depolymerization |
| Calcium Oxalate Structural Change Onset | ~ 375 | °C | Reaction occurs near Tc of water |
| Heating Rate (XRPD/Raman) | ~ 10 | °C/min | Rate for in situ time-resolved experiments |
| X-ray Wavelength (λ) | 0.509175 | Å | Used for hard X-ray micro analysis (HXMA) |
| Raman Laser Excitation Wavelengths | 514.5 or 785 | nm | Used for spectral acquisition |
| Gasket/Chamber Thickness | 250 | µm | Stainless-steel constraint for high pressure |
| Sample Chamber Outer Diameter (o.d.) | 250 | µm | Extreme confinement of sample |
| XRPD Detector Exposure Time | 60 | s | Fast acquisition for time-resolved profiling |
Key Methodologies
Section titled “Key Methodologies”The experiment successfully integrated XRPD and micro-Raman measurements by utilizing the specialized optical properties of the diamond anvil cell, requiring precise alignment and specialized SCD components.
- HDAC Setup: A Bassett-type Hydrothermal Diamond-Anvil Cell (HDAC) was used, enabling in situ measurements under high temperature and pressure.
- Sample Preparation: Analytes (cellulose, calcium oxalate, hydroxyapatite) were loaded with distilled water into a 250 µm outer diameter chamber defined by a 250 µm thick stainless-steel gasket.
- Temperature Control: Samples were heated at a controlled rate of ~10 °C/min under a constant flow of nitrogen (N2).
- Raman Data Acquisition: Micro-Raman spectra were collected using 514.5 nm or 785 nm laser excitation and a super long-working distance 20x objective, focusing on chemical changes (e.g., loss of cellulose vibrational modes).
- XRPD Data Acquisition: Hard X-ray micro analysis was performed at the Canadian Light Source (HXMA beamline, λ = 0.509175 Å) using a 250 µm pinhole to prevent interference.
- Simultaneous Measurement Strategy: The HDAC was mounted on a motorized swivel stage and rapidly shuttled between two positions (Raman imaging/Position 1 and X-ray measurement/Position 2) to perform sequential structural and chemical analysis over a short total heating duration (45-60 minutes).
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”This research validates the demand for ultra-high-quality Single Crystal Diamond (SCD) components capable of withstanding extreme conditions while maintaining required optical and X-ray transparency. 6CCVD is uniquely positioned to supply and customize the materials necessary for replicating and advancing these HDAC experiments.
| Research Requirement / Application Challenge | 6CCVD Applicable Materials | 6CCVD Customization Potential & Capability |
|---|---|---|
| High-Pressure Containment (DAC Anvils) | Optical Grade Single Crystal Diamond (SCD) | SCD is mandatory for its unrivaled strength, ensuring mechanical stability up to GPa pressures required for SCW research. |
| Optical Access (Raman Excitation/Detection) | Ultra-Low Birefringence SCD | Provides superior signal-to-noise ratio by minimizing background scattering and depolarization effects, crucial for observing weak Raman signals from biomass. |
| X-ray Transparency (Synchrotron XRPD) | High-Purity, Low-Defect SCD | Ensures maximum transmission and minimum X-ray scattering/absorption, critical for fast (60 s exposure) data collection using hard X-rays (λ = 0.509175 Å). |
| Custom HDAC Geometry & Mounting | Custom Dimensions and Orientation (Plates up to 125 mm) | 6CCVD supplies precision-cut SCD plates (up to 500 µm thickness) tailored for specific anvil designs (e.g., Bassett-type) and crystallographic orientation, enhancing X-ray diffraction geometry. |
| Integrated Temperature Sensing/Control | Custom Metalization (Ti/Pt/Au/W) | 6CCVD offers in-house capabilities to deposit custom metal electrodes onto the SCD face, allowing integration of resistive heaters or thermal sensors for highly accurate, in situ temperature control (essential for kinetic studies near Tc). |
| Optical Quality for Imaging | Precision Polishing (Ra < 1 nm for SCD) | Maintains exceptional surface flatness and parallelism, ensuring high-quality optical imaging and effective use of long-working distance objectives (20x) during demanding in situ experiments. |
Engineering Support
Section titled “Engineering Support”This research demonstrates the potential of utilizing diamond platforms for Hydrothermal Biomass Conversion and High-Pressure/High-Temperature (HPHT) Spectroscopy projects. 6CCVD’s in-house PhD team provides expert consultation to select the optimal SCD grade, orientation, and polishing specifications required to achieve superior experimental results under demanding near- and supercritical conditions.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract The applications of synchrotron X‐ray powder diffraction ( XRPD ) and laser micro‐Raman techniques in an examination of the dissolution, transformation, and gasification of pure cellulose and models for biomass residue under hydrothermal conditions in a diamond‐anvil cell are reported. The results contribute to the measurement of in situ time‐resolved profiles of biomass reactions, catalyst stability, and residue formation that occur in aqueous fluids at near‐ and supercritical conditions.
Tech Support
Section titled “Tech Support”Original Source
Section titled “Original Source”References
Section titled “References”- 2011 - Hydrothermal Raman microscopy studies of manganese carbonyls
- 2009 - Naphthalene combustion in supercritical water flames [Crossref]
- 2011 - Evolution of naphthalene and its intermediates during oxidation in subcritical/supercritical water [Crossref]