ACTIVE PACKAGE

Abstract

An active package having LTA zeolites exchanged with palladium is described. This solution is capable to improve the quality of the gaseous atmosphere within the package itself, with particular reference to the presence of ethylene. This solution provides improved performance when the package is accidentally exposed to hydrocarbon vapors and provides benefits in terms of reliability in the ethylene control.

Claims

1. An active package containing LTA zeolites exchanged with palladium, wherein the amount of palladium is comprised between 0.1 wt % and 5 wt %, preferably said palladium amount is comprised between 0.5 and 2.5 wt %.

2. The active package according to claim 1, wherein said LTA zeolites are present in an amount greater than 75% in weight of the total zeolite content.

3. The active package according to claim 1, wherein an amount of exchanged zeolite is comprised between 0.3 μg and 30 μg per gram of weight of a perishable fresh food.

4. The active package according to claim 1, wherein said zeolites exchanged with palladium are in the form of powders with average size comprised between 50 nm and 500 μm.

5. The active package according to claim 4, wherein said powders are contained in a permeable bag placed within the package.

6. The active package according to claim 5, wherein the material for the permeable bag is selected from the group consisting of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), ethylene-vinyl acetate (EVA), styrene-ethylene-butylene-styrene (SEBS), polylactic acid (PLA), and polyesters.

7. The active package according to claim 4, wherein said powders are dispersed in a polymeric material.

8. The active package according to claim 7, wherein said polymeric material is selected from the group consisting of acrylics, acrylics-styrene, -vinyl, and -alkyd copolymers, urethane-acrylics, aliphatic-urethane, urethanes, polyesters, epoxies, polyurethanes, polyamides, melamine, polystyrene, phenolic resins, ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVA), and waterborne or water reducible latex.

9. The active package according to claim 7, wherein said polymeric material containing the dispersed powders is in the form of a film having thickness comprised between 5 and 50 μm.

10. The active package according to claim 9, wherein the wt % of LTA palladium exchanged zeolites with respect to the film weight is comprised between 0.01 wt % and 20 wt %.

11. The active package according to claim 10, wherein the wt % of palladium exchanged zeolites with respect to the film weight is comprised between 10 wt % and 20 wt %.

12. The active package according to claim 10, wherein the wt % of LTA palladium exchanged zeolites with respect to the film weight is comprised between 0.01 wt % and 5 wt %.

13. The active package according to claim 9, wherein said film is attached onto an inner surface of the active package.

14. The active package according to claim 9, wherein said film is a constituent portion of the active package itself.

Description

EXAMPLE 1

Sample Preparations

Sample 1 (S1)

[0021] Palladium exchanged LTA zeolites were prepared using ion exchange process. LTA zeolites used have an average size comprised between 100 nm and 10 μm, with 50% of the zeolites below 2 μm and 75% below 5 μm.
10 g of zeolites were dispersed in a solution of a palladium salt (e.g nitrate salt or chloride salt), then filtered on a nylon membrane and thermally treated to promote the solvent evaporation.
Resulting palladium exchanged amount is about 1.5 wt % by weight over the LTA zeolites weight, as evaluated by ICP Mass Spectrometry.

Sample 2 (S2)

[0022] LTA-H zeolites were prepared using ion exchange process, starting from LTA-Na zeolites with particle size below 5 μm (X75). 20 g of zeolites were added to aqueous solution of NH.sub.4NO.sub.3. The suspension was stirred at room temperature, and then was filtered with a 0.45 mm membrane filter and finally dried in an oven. The isothermal treatments, on ammonium-exchanged zeolite, were carried out in the air by furnace, at 500° C. for 5 h, to achieve LTA-H.
The ICP analysis showed a decrease in the content of Na in zeolites LTA-H as expected. The amount of Na in LTA-Na is 14.0% wt instead in LTA-H is about 5.2% wt. Palladium exchanged LTA-H zeolites were prepared using the same process previously reported for sample 1 (S1).

Comparative Samples C1-C3

[0023] Some comparative samples were different type of “raw” (not exchanged with palladium) zeolites. LTA-Na, ZSM-5 (NH.sub.4) and Faujasite (Na) were selected.

Comparative Sample C4

[0024] A comparative sample palladium exchange ZSM-5 (H) was obtained, first, by thermal treatment, at 500° C. for 5 h in air, of the sample ZSM-5 (NH.sub.4) (C2) and then, by ion exchange process as follows. 10 g of ZSM-5 (H) zeolites were dispersed in a solution of a palladium salt, later filtered on a nylon membrane and dried in an oven at 100° C. overnight.

[0025] All samples that have been described above are summarized in table 1

TABLE-US-00001 TABLE 1 Sample ID Zeolite type Size (X50) Size (X75) Pd exchanged S1 LTA-No 2.0 μm 5.0 μm Y (1.5 wt %) S2 LTA-H 2.0 μm 5.0 μm Y (1.5 wt %) C1 LTA-Na 2.0 μm 5.0 μm N C2 ZSM-5 (NH.sub.4) 4.9 μm 7.0 μm N C3 Faujasite (Na) 4.0 μm 6.0 μm N C4 ZSM-5 (H) 5.0 μm 7.0 μm Y (1.5 wt %)

EXAMPLE 2

[0026] Different types of zeolites (S1, C1-C4) were tested under different conditions. Measurements were carried out in a microbalance with conditioned sample chamber. Zeolites (10 mg) were activated at 180° C. under vacuum overnight and then tested under C.sub.2H.sub.4 10 mbar partial pressure and different humidity level.

[0027] The obtained results are reported in table 2.

TABLE-US-00002 TABLE 2 C.sub.2H.sub.4 % wt C.sub.2H.sub.4 % wt @ 22° C.—dry @ 22° C.—15 mbar H.sub.2O S1 2.2  0.30 C1 2.3  Negligible C2 2.1  Negligible C3 0.65 negligible C4 8.27 1.38

[0028] Among the prepared and tested samples, only samples S1 and C4 are capable to maintain an acceptable ethylene removal capability in the presence of a high humidity level, even if a capacity loss of about 80% has been observed if compared to anhydrous conditions, for both samples S1 and C4.

EXAMPLE 3

Hydrophobicity Tuning

[0029] Different types of LTA zeolites were tested under H.sub.2O partial pressure to determine the hydrophilic affinity. Measurements were carried out in a microbalance with conditioned sample chamber. Zeolites were activated at 180° C. under vacuum overnight and then equilibrated under nitrogen atmosphere before introducing the H.sub.2O pressure. Sorption results have been reported in table 3.

TABLE-US-00003 TABLE 3 H.sub.2O Sorption capacity Sample ID (15 mbar) S1 18.0% wt S2  4.4% wt

[0030] Sample S2 shows a lower H.sub.2O sorption capacity revealing a lower hydrophilic behavior. In case of ethylene gettering activity, this sample is able to ensure lower H.sub.2O competition. This confirms that, when required, LTA zeolites can be obtained in acid form, limiting the jeopardizing effect of high humidity on the sorption of ethylene molecules.

EXAMPLE 4

Cyclohexane Contamination

[0031] Different types of zeolites (S1, S2 and C4) were tested under cyclohexane partial pressure. For a critical set of characteristics (molecule critical diameter, vapor density, liquid density, vapor pressure, and boiling point) cyclohexane can be adopted like a tester molecule to evaluate the sorption capacity of adsorbing materials like zeolites for all the typical volatile organic compounds (VOCs) released by transportation fuels. A list of these typical VOCs includes aromatics (i.e. benzene, ethylbenzene, p-, m-xylene, o-xylene) and cycloalkanes (i.e. cyclohexane, methyl cyclohexane).

[0032] Measurements were carried out in a microbalance with conditioned sample chamber. Zeolites were activated at 180° C. under vacuum overnight and then equilibrated under nitrogen atmosphere before introducing the C.sub.6H.sub.12 pressure.

[0033] Table 4 shows gravimetric test results regarding the quantitative evaluation of the cyclohexane adsorption for samples 1 and 2, and comparative sample 4, with comparable level of sample exposure to the cyclohexane vapors (0.1 mbar partial pressure).

TABLE-US-00004 TABLE 4 C.sub.6H.sub.12 Sorption capacity Sample ID (0.1 mbar) S1 0.21 S2 0.13 C4 4.16

[0034] Despite the bigger accessible volume for samples S1 and S2 (21.43% vs. 9.81%) due to the zeolite framework characteristics, Pd-exchanged LTA zeolites show a lower sorption capacity (one order of magnitude) for cyclohexane than Pd-exchanged ZSM-5 (H) zeolites (sample C4).

[0035] The results we have reported in table 4 demonstrate that LTA zeolites can work as sorber material for ethylene minimizing the risk of contamination by other VOC's present under typical fruit transportation conditions. High C.sub.6H.sub.12 sorption capacity for samples C4 reveals for it a stronger competition of VOCs for ethylene gettering, i.e. a correspondent loss in ethylene sorption capacity (about a 50% loss if compared to the C4 sorption capacity reported in example 1).

[0036] LTA zeolites (S1 and S2) have shown a limited absorption of cyclohexane: the decrease of their sorption capacity of ethylene can be therefore estimated in the range of 5% (S2) to 10% (S1) if compared to sorbed amount in the anhydrous conditions of example 1.

[0037] As a consequence, when a manufacturer has to design a getter system containing at least a component of LTA zeolites he can reduce the introduction of zeolites in excess, that is required in a massive amount for ZSM-5 zeolites in order to prevent accidental contamination during transport: this involves evident advantages in terms of both cost saving and manufacturing conditions.