KLK750: Thermal Processing of Low-Grade Glycerol to Alcohols for Biodiesel Fuel Production

Principal Investigator:

Brian He

Project Objectives:

The PI proposes research on biofuel technology that is in accordance with the Goal 2 of the NIATT’s Prospectus for Tier 1 Center Competition, i.e., “improve the quality and economic viability of biofuels and reduce the environmental impacts and improve the fuel economy and safety of motorized vehicles (including cars, transit vehicles, and recreational vehicles) to protect the nature and built environment,” and directly under the Strategy 2.3 of Goal 2 of the Prospectus, namely, “develop new biofuels production methods and techniques for reducing biofuels emissions.”

Specifically, the objective of this project is to conduct an experimental research on converting the low-grade glycerol derived from biodiesel production to short-chain primary alcohols of methanol, ethanol, and/or propanols, or their mix, and applying back to the biodiesel production process. The specific tasks include:

Task 1. Development and testing of a reactor system that is capable of conducting high temperature, high pressure chemical reactions of hydro-thermal conversion
Task 2. Establishment of analytical procedures for detecting and identifying the conversion products
Task 3. Screening and confirmation of major process parameters
Task 4. Project Phase I summary and interim report
Task 5. Thorough investigation on the effects of process parameters
Task 6. Process optimization to maximize alcohol production
Task 7. Project summary and final report

This project will be accomplished in two phases in 28 months:
Phase I: Reactor system preparation and process parameter investigation.
The research in this stage includes Tasks 1 to 4 and will be conducted from Months 1 thru 12 (Aug. 2007 to Aug. 2008)
Phase II: Process parameter evaluation and process optimization. The research in this stage includes Tasks 5 to 7 and will be conducted from Months 13 thru 28 (Aug. 2008 to Dec. 2009.

Task Descriptions:

Introduction to the Concept

To explore a novel way to utilize the low-grade glycerol, this project proposes a thorough study on converting glycerol (a polyhydric alcohol or triol) to short-chain monohydric alcohols, such as methanol and ethanol or their mix, for application back to the biodiesel production process. The proposed method is hydro-thermochemical conversion, e.g., thermal cracking or pyrolysis and liquefaction in the presence of a reducing agent. Pyrolysis is a chemical reforming process of biomass or other organic matters which are depolymerized and reformed in a heated and oxygen-absent enclosure. Depended on heating rate and operating temperature, pyrolysis is also further categorized as flash pyrolysis (400 to 600°C at >100°C/s heating rate) and fast pyrolysis (>600°C but lower heating rate). The products of pyrolysis are primarily liquid (hydrogenated oils) and solid (char), and some gaseous (methane, carbon monoxide, carbon dioxide, etc). The proportions of the products are dependent on factors such as operating temperature, pressure, oxygen content and biomass feedstock type. Liquefaction is a thermochemical conversion process of biomass or other organic matters into primarily liquid oil products in the presence of a reducing reagent, e.g., carbon monoxide or hydrogen. Liquefaction is usually conducted in an environment of moderate temperatures (300 to 400°C) and high pressures (e.g., 5~20 MPa or 720~2900 psi). Liquefaction is superior to pyrolysis if liquid products are targeted and the carbon is fully utilized (pyrolysis sacrifices some carbons to char in exchange of liquids).

The PI has conducted projects on thermochemical conversion of biomass for hydrogenated oils and gained experiences in liquefaction processes (He et al., 2000a,b; 2001a,b,c).

Compared to lingo-cellulosic biomass, glycerol is a perfect feedstock for liquefaction. It contains consistent constituent that leads to consistent products. To convert glycerol to monohydric alcohols, a combination of pyrolysis and hydro-reforming under a reducing environment is needed, i.e., the three-carbon chain is chopped one- or two-carbon molecules, and one of the hydroxyl group (-OH) is removed as CO2 or H2O, depending the reducing agent added. The candidate reducing agents include carbon monoxide and hydrogen. Ideally, each mole of liquid glycerol will yield one mole methanol and one mole ethanol, which account for two thirds of the alcohol requirement for biodiesel production from vegetable oils. Even more ideally, if each mole of liquid glycerol will yield three moles of methanol, the alcohol required for biodiesel production could be self-sustained from vegetable oils. The chemical conversion and products are illustrated below:

However, the composition of the products is heavily affected by the operating conditions. Other products that are also possibly derived from this process include methane (CH4), n-propanol (CH3CH2CH2-OH), i-propanol (CH3CH-OHCH3), and char.

A feasibility study supported by NIATT UTC grant has been conducted previously. The preliminary investigation has shown encouraging results (an example data set is shown below). The targeted products, e.g., methanol, ethanol, and propanol, were obtained as expected through the hydro-thermal conversion process. Due to the nature of this research, and the limited accessibility to the specialty reaction equipment, detailed in-depth investigations were not conducted.

Example Results of Liquid Product Analysis of Feasibility Study

[a] duplicate

Task 1. Development and testing of a reactor system that is capable of conducting high temperature, high pressure chemical reactions of hydro-thermal conversion

The reactor system, capable of conducting high temperature, high pressure chemical reactions, is the key to the project. The desired features of the reactor system will include precise temperature and pressure controls, adequate agitation with control, liquid and gaseous sampling mechanism, and product condensation/removal device. A commercially available laboratory reactor (300 mL capacity) that meets the need of this project is proposed to be purchased from Parr Instrument (Peoria, IL). As a safety measure, an enclosed, metal-framed chamber with sufficient ventilation will be constructed to host the reactor. Accordingly, modifications will be made to streamline the whole system specifically for the proposed project, which include customized feeding, sampling, and temperature/pressure controls.

Task 2. Establishment of analytical procedures for detecting and identifying the products

Valid analytical methods are the key to obtaining reliable information. Therefore, analytical procedures will be carefully developed, evaluated, and calibrated before experimental data can be collected for processing and analysis. Gas chromatograph (GC), available at the PI’s Biofuel Research Laboratory, will be the major tool for analyzing samples. GC-MS will be also used, when necessary, to identify unknown substances in the products besides the targeted alcohols. Analytical procedures will be fine-tuned to improve repeatability and sensitivity.

Task 3. Screening and confirmation of major process parameters Previous feasibility study revealed that operating temperature is one of the influential parameters.

However, the effect of operating temperature on the glycerol conversion process was complicated by other parameters. Preliminary results also indicated that glycerol does not decompose at the temperature claimed by many literature sources. Due to lack of information on similar research in the literature, all possible process parameters that potentially affect the glycerol conversion process have to be explored for a full understanding. Preliminary experiments will be carried out first to explore a wide range of reaction conditions to identify the key influential parameters. These parameters will include those identified from previous fundamental research, such as temperature, pressure, reaction time, reducing agent, etc., but also the engineering aspects of the process such as the reaction equilibrium, mass transfer versus agitation, effect of transit stage, and effect of heat transfer rate. During this period of time, the reactor system will be fully tested and possible barriers and limitations will be diagnosed and corrected. This process is necessary before a fully implemented research plan be carried out.

Task 4. Project Phase I summary and interim report Upon the completion of this stage’s research, a written summary will be prepared.

Included in this summary, the following materials will be documented:

• A reactor operating procedure to be used for safe operation of the system
• A standardized procedure for product analysis and data processing
• A summary on key process parameters and an analysis on their relative importance
• A detailed experimental design for Phase II research

This Phase I summary will be formatted/modified into an interim report to NIATT. A manuscript will be prepared out of the Phase I research and submitted/presented to a technical conference. The PI will work with NIATT and the Idaho Research Foundation to identify the feasibility/ possibility of applying patents on the technology resulted from this research.

Task 5. Thorough investigation on the effects of process parameters

Accomplishment of Phase I research will provide a good knowledge how the Phase II research will be conducted. An improved reactor system for process research will aim at achieving better reactivity of glycerol hydro-thermal conversion. A thorough investigation on the effects of process parameters will be conducted systematically through carefully formulated experimental designs. The experimental design will be constructed by computer-aided design software according to statistical models. The information obtained will be maximized and the number of experiments will be kept minimal. Due to the large number of process variables, even guided by experimental design, the work load of the experimentation is expected to be high. The nature of such a reaction system, e.g., high temperature/pressure, involvement of reducing reagents such as carbon monoxide, will also determine the length of time of each experiment. Therefore, this task is expected the most time consuming part of the project and will dominate the Phase II research.

Task 6. Process optimization to maximize alcohol production Experimental data collected will be analyzed statistically. The working conditions will be optimized based on statistical models to achieve the best primary alcohol yield. The statistical model, after being verified experimentally, will be analyzed and compared against the kinetics obtained previously. A comprehensive model will be proposed to describe the overall conversion process.

Task 7. Project summary and final report

Once the experimental part of this project is completed, a final written report will be prepared and submitted to NIATT. The following materials will be documented:

• The methodology of this research, including the equipment and devices, experimental procedures, materials, analytical procedures
• Experimental results and discussions
• Conditions for process optimizations and system models
• Conclusions on the project and recommendation for future research and/or technological development

Two manuscripts are expected to be prepared and submitted to peer-reviewed journal/s. Meanwhile, the experimental results will be disseminated through professional meetings and other means of disseminations.

Milestones

Phase I (08/07 – 08/08)
Aug.21, 2007 Project starts.
Dec. 31, 2007 Reactor is purchased, installed and tested; analytical procedures using standard chemicals are developed and established.
May 15, 2008 Trial experiments are conducted and all process variables potentially affecting the process efficiency are identified and tested; analytical procedures are fine-tuned through analyzing the conversion products and improved into standard procedures for Phase II.
July 31, 2008 Experimental work is completed according to Tasks 1 – 3 of Phase I.
Aug. 31, 2008 Project summary of Phase I is prepared and an interim report is submitted to NIATT.
Phase II (08/08 – 12/09)
Aug. 2008 Project of Phase II starts.
May 15, 2009 Thorough experimental investigation on process parameters is completed (Task 5).
Aug. 31, 2009 Process experimental optimization is completed.
Dec. 31, 2009 Experimental data are summarized, processed, and analyzed; final project is prepared and submitted to NIATT; two manuscripts are prepared and submitted to peer-reviewed journal(s).

Budget Information:

UTC funds committed to this project: $78,092

Student involvement

One (1) graduate student will be in charge of project on experiment preparation, execution, and data collection. Undergraduate researchers, two (2)-students/year is expected, will be involved in the project to assist in data collection and experimental operations. Additional two (2) undergraduate researchers, supported by other sources, will participate in project preparation.

The PI recognizes the importance of involving students in research. Through participation of the project, students will integrate their education and research in the areas of bioenergy and bioproducts, and prepare them as scientists and engineers for the emerging biorefinery industry. Students will also be better able to see the potential applications of their research to real world problems in bio-based industries. As a very important part of higher education, students will be encouraged and sponsored to participate in technical conferences and other professional society activities to enrich their experience.

Technology Transfer Activities

Results from this project will be reported and published in various forms of deliverables, e.g., journal papers, professional presentations, technical posters, and possibly patents. Information will also be prepared for industry and other sub-technical audience to promote application of the resulting technology in commercial biodiesel production. Acknowledgement will be addressed in all applicable deliverables to the NIATT/DOT UTC program.

Upon the accomplishment of this two-year project, effort will be desperately made to solicit external support and/or industry collaborations to conduct pilot scale research. Ultimately, the technology will be developed into commercial applications.
As soon as experimental data are collected, the PI will work with NIATT and the Idaho Research Foundation to convert any possible intellectual properties into patents.

Potential Benefits of the Project

This project contributes greatly to the current knowledge base on alternative utilization of crude glycerol and benefits the whole biodiesel industry and enhances the research capability and continued success of biodiesel research and utilization at the University of Idaho. Most importantly, successful implementation of the project will produce primary alcohols, e.g., methanol and/or ethanol. Currently, methanol is the industrial standard alcohol feedstock. Methanol, as a matter of fact, is made primarily from fossil-based resources such as natural gas. Biodiesel made from such methanol and vegetable oil is not, strictly speaking, truly a “bio-based” product.

Through this project, the PI will explore the process of producing primary alcohols, methanol and/or ethanol, from the by-product glycerol and use the alcohols back in the biodiesel production process. Ideally, biodiesel could be produced solely from vegetable oils that provide all the needed constituents. This will make the biodiesel industry completely independent from fossil-based resources and the biodiesel will be truly a bio-based product, which in turn will further increase the energy security of our country and enhance the environmental benefits of biodiesel.
It is expected that this project will results in a good knowledge of converting off-grade glycerol from biodiesel production to alcohols which are the feedstock for biodiesel production. The outcome from this project will enhance the sustainability of biodiesel by adding value to the by-product and producing needed feedstock to offset biodiesel production costs.

Project status:

Active

Final Report: