AMBIENT TEMPERATURE OXIDATION CATALYST FOR ETHYLENE CONTROL IN FRESH PRODUCE CONTAINERS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: SMALL BUSINESS GRANT
• Reporting Frequency: Annual
• Accession No.: 0228765
• Grant No.: 2012-33610-19528
• Proposal No.: 2012-00026
• Project Start Date: May 15, 2012
• Project End Date: Jan 14, 2013
• Grant Year: 2012
• Program Code: [8.13]- Plant Production and Protection-Engineering

Recipient Organization
TDA RESEARCH, INC.
12345 WEST 52ND AVENUE
WHEAT RIDGE,CO 80033

Performing Department
(N/A)

Non Technical Summary
The respiration of fresh fruits and vegetables (FF&V) converts oxygen from the surrounding atmosphere into carbon dioxide, moisture and ethylene. While ethylene is used under controlled conditions as a ripening agent, the presence of even small amounts of ethylene gas in shipping and storage containers causes most fresh produce to deteriorate faster, potentially spoiling it before it reaches the store or consumer. Current ethylene control technology is based on potassium permanganate filters. While they are effective, they pose logistics problems because they must be frequently replaced. In addition, the used filters are considered hazardous waste and require special disposal procedures. TDA Research, Inc. (TDA) proposes an ambient temperature oxidation catalyst that could be integrated into current shipping containers and storage facilities to eliminate ethylene. The catalytic oxidizer does not require any replacement and disposal of the used media. The high activity of the catalyst at low temperatures eliminates the need to heat the air that flows through it and reduces operating costs. In Phase I, we will prepare and evaluate various catalyst formulations under representative conditions to prove the technical feasibility of the concept and carry out an economic analysis to evaluate its commercial viability.

Animal Health Component

50%

Research Effort Categories

Basic

(N/A)

Applied

50%

Developmental

50%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
503	1099	2000	15%
503	1199	2000	15%
503	1430	2000	10%
503	1499	2000	10%
503	1099	2020	15%
503	1199	2020	15%
503	1430	2020	10%
503	1499	2020	10%

Knowledge Area
503 - Quality Maintenance in Storing and Marketing Food Products;

Subject Of Investigation
1499 - Vegetables, general/other; 1099 - Tropical/subtropical fruit, general/other; 1430 - Greens and leafy vegetables; 1199 - Deciduous and small fruits, general/other;

Field Of Science
2020 - Engineering; 2000 - Chemistry;

Keywords

fresh fruits and vegetables, ff&v, perishable, ethylene, oxidation,

ambient temperature, oxygen

Goals / Objectives
The respiration of fresh fruits and vegetables (FF&V) converts oxygen from the surrounding atmosphere into carbon dioxide, moisture and ethylene. While ethylene is used under controlled conditions as a ripening agent, the presence of even small amounts of ethylene gas in shipping and storage containers causes most fresh produce to deteriorate faster, potentially spoiling it before it reaches the store or consumer. Current ethylene control technology is based on potassium permanganate filters. While they are effective, they pose logistics problems because they must be frequently replaced. In addition, the used filters are considered hazardous waste and require special disposal procedures. The objective of this project is to develop a compact catalytic oxidizer that will remove ethylene from the fresh produce container boxes enabling to increase the post-harvest life of the produce. The new catalyst will work at ambient temperature, taking advantage of the existing flow circulation system in the refrigerated containers. This will greatly reduce the barriers to adoption. In the Phase I work, our primary objective is to develop an effective catalyst that oxidizes the ethylene into CO2 and water. In Phase I, we will demonstrate the technical feasibility and economic viability of using this catalyst for ethylene oxidation at low temperatures and at very low concentrations. We will synthesize several of catalyst formulations and screen them based on their mechanical and physical properties. We will then evaluate them extensively at the bench-scale to determine their catalytic activity under representative conditions. We will select the best catalyst formulation and demonstrate stable performance for a minimum of 500 hr to assess life and durability. Based on experimental results, we will carry out a preliminary design of the catalyst cartridge and the integrated refrigeration system that can treat the air flow in a 48 ft refrigerated container (~3,500 cfm air flow). Based on experimental results, we will carry out an economic analysis to evaluate the commercial viability of the concept. Fresh fruits and vegetables make up a $70 billion annual global industry while 25-46% (~100 billion pounds) of it annually is wasted due to spoilage. TDA proposes an ambient temperature oxidation catalyst that can eliminate ethylene in storage and shipping containers. The new technology will allow slowing down the maturation of the fruits and greatly reduce spoilage, increasing the post-harvest storage life. A longer shelf life allows producers, handlers and sellers to spread availability over periods of strong and weak demand, maintaining supply and stabilizing cost, while eliminating the waste will reduce the overall energy consumption producing the unit volume of produce.

Project Methods
TDA Research, Inc. (TDA) proposes to develop a low temperature catalyst that can oxidize ethylene into CO2 and H2O to control its concentration in the FF&V containers. The catalyst cartridge will be highly compact and easily integrated to the gas circulation loop of the refrigeration system. The catalytic oxidizer does not require any replacement and disposal of the used media. portion or all the compartment return air goes through the ambient temperature oxidation catalyst, where a high per pass conversion is achieved (i.e. greater than 90% per pass removal efficiency is targeted). The ethylene free gas will then be returned to the container. Although it is possible to warm the gas temperature to increase the ethylene oxidation activity, our catalyst will operate at ambient temperature to eliminate the energy cost associated with the pre-heating of the air.

Progress 05/15/12 to 01/14/13

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? In this Phase I SBIR project we prepared and evaluated different catalyst formulations under representative conditions to prove the technical feasibility of the concept and carried out an economic analysis to demonstrate its commercial viability of the concept. We showed that the catalyst is highly effective in converting ethylene into CO2 and H2O, generates no undesirable by-products and maintains its performance over a long period of time. A preliminary economic analysis of the system shows a clear cost advantage over the current, one-time use permanganate filters. In the Phase I work, we identified a catalyst formulation consisting of precious metal nanoparticles that are highly dispersed on a high surface area titanium oxide (TiO2) support. Because of the low coordination of metal atoms (i.e., each atom only has a small number of neighbors), the catalytic atoms in these nano-clusters interact strongly with ethylene and activate its reaction with oxygen, carrying the reaction all the way to the complete combustion products of CO2 and H2O (no partial oxidation products such as CO and ethylene oxide are formed). The catalyst is prepared by a simple, low cost, scalable vapor phase synthesis method. The metal particle size is controlled by the size of the metal-organic precursor and the deposition rate, which can be adjusted simply by controlling deposition temperature. In this project we synthesized a large number of catalysts formulations and evaluated their performance under representative conditions to identify the ones with the highest activity and turnover efficiency (e.g., mmol ethylene oxidized per g of metal per second). To reduce the precious metal content and the catalyst cost, we have successfully prepared the active phase as a thin coat applied to the pre-formed support pellets/granules (often referred to as an eggshell or skin catalyst). The active sites are only on the outer skin, providing high accessibility and eliminating mass transfer limitations to ensure highest utilization of the precious metal. Our catalysts could achieve a high ethylene oxidation over a range of ethylene concentrations (0.1-10 ppmv), gas-solid contact times (0.1-1 miliseconds), moisture levels (0-90% relative humidity) and temperatures (4-20oC). In these tests, we confirmed complete destruction of ethylene via oxidation to CO2, without forming any undesirable products (ensured by the complete closure of carbon balance). We have demonstrated catalyst durability in excess of 220 hr of testing. Throughout the Phase I durability test, the catalyst maintained its activity. Post-analysis characterization also confirmed that its physical and chemical properties (e.g., crush strength, surface area) were unchanged. We designed a catalytic filter that can directly replace the permanganate sachets that are used in the conventional refrigerated containers. Unlike the permanganate sorbents that needs to be replaced in every three to four months, the catalyst bed could theoretically be operated through the entire life of the container (typically 12 years) without requiring any replacement. Although the initial cost of TDA’s catalytic cartridge will be higher than the permanganate sachets, due to the savings in both labor and replacement costs we expect that the annual operating cost of the new catalysts will breakeven with the conventional permanganate based control systems in less than one year.

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