FAQs

It is recommended to discuss with Zeochem theproposed changes so that a system review and design simulations can be run to determine if any operating changes are necessary or recommended. Zeochem can further check to make sure that all changes fall within recommended operating guidelines, and propose alternatives ifchanges may be problematic.

Yes, they are.

Yes, Zeochem can regenerate used molecular sieve. Contact Zeochem to discuss a tailored-solution for your application.

ZEOflair powders’ ability to remove odor/VOC compounds at elevated temperatures is diminished. However, as the material starts to cool down, the odor/VOC compounds that are still left in the formulation will be adsorbed by ZEOflair powders

Yes.Purmol inventory is maintained at our warehouse located in Louisville, KY.Purmol is also available through approved US and Canada distribution partners.

Yes, Zeochem can regenerate used molecular sieve. Contact Zeochem to discuss a tailored-solution for your application.

Yes, we can, but we prefer and always recommend to use FCA, CFR/CIF and DAP incoterms for smoother and more cost effective deliveries; Zeochem can help with freight organization.

Yes, Zeochem products can easily withstand this pressure range

No, Zeochem product can be used for direct oxygen concentration to 99+% purity in PSA system. Silver exchanged molecular sieve is typically used in these applications. Although Zeochem does not have a commercially available silver exchanged molecular sieve, we are available to discuss specific requests for silver exchanged molecular sieves on a case by case basis.

Yes, we do have a range of products suited for use in Biogas upgrading

No, Zeochem does neither manufacture nor trade CMS

No, Zeochem has partnered with Headwater Solutions to provide the design and construction of the units. To learn more, please visit Headwater Solutions.

Please contact Zeochem at info@zeochem.com orcomplete the new product request form by visiting our products page on our ZEOtope website.

It is recommended to discuss with Zeochem theproposed changes so that a system review and design simulations can be run to determine if any operating changes are necessary or recommended. Zeochem can further check to make sure that all changes fall within recommended operating guidelines, and propose alternatives ifchanges may be problematic.

If there are changes in the normal dewpoint trendlines or signs of increasing dewpoints during normal adsorption cycles, it may be indication that water breakthrough is occurring, and the sieve may soon require change out. Other indicators include high or increasing pressure drop across the sieve beds, in-line strainers, and heat exchangers, changes in normal flow rates and patterns, and increased difficulty maintaining consistent flow, temperature, or pressure. In many cases performance history together with the current performance and a design simulation run will provide a good indication of expected remaining life of the sieve. When additional or more accurate data is needed to predict sieve life, a breakthrough test can be performed on the sieve beds or on the weakest bed (if there is a known weaker bed).

Schedule the change out well ahead of time, preferably during an already scheduled shutdown or turn around. Order and have all needed products and supplies on site well ahead of time to avoid any delays. Make sure all contractors, plant personnel, and equipment will be ready to begin the morning of the scheduled start, with any necessary orientation, training, etc. completed in advance. Follow the Zeochem guidelines and recommendations for unloading and reloading the sieve to streamline the process and avoid delays. Have contingency plans in place should there be weather or unexpected delays that occur.

Purmolpowder in one-component systems should be addedprior to the addition of the prepolymer. In two-component systems, we recommend the addition of2.5 wt% – 5 wt% Purmol powder to the polyolcomponent. This must be stirred thoroughly to allowtime for Purmol to adsorb the water before the addition ofthe isocyanate.

The water capacity is the percent by weight that the sieve adsorbs. At equilibrium, the adsorption is basically driven to completion to determine the absolute maximum amount of potential adsorption. This is most often used as a general baseline measure of the sieve’s quality and ability to adsorb water. Dynamic capacity is the working capacity that is expected from the sieve to avoid breakthrough of water in an actual process. The design simulation determines this capacity based upon the feed and regeneration stream compositions and conditions, and the water concentration, as well as the concentration of other contaminants. It involves not only the equilibrium capacity, but calculation of the mass transfer zone, effects of other contaminants, andaging of the sieve over time. All of these factors contribute to the difference between achievable water adsorption in service and the theoretical maximum water loading for the sieve.

Shelf life of an unopened drum, properly stored, is warranted for 5 years.In practice it can remain fresh indefinitely as long as the drum remains sealed and properly stored. The sieve is chemically stable, and does not break down over time in storage. Once a drum is opened, the material should be consumed quickly. If a partial drum needs to be stored for later use, it is recommended to close the bag.

Stored sealed in factory packaging until ready for use. It is recommended to handle the material in a climate-controlled environment, ideally with lowest %rH possible to reduce the moisture pickup from the ambient air. Sieve is a powerful desiccant and will quickly adsorb water from the air, and so minimizing exposure during sieve bed loading is crucial to minimize N2 capacity loss and thus maximize performance in O2 concentrators.

To protect yourself from injury, use the new ZEOtope ampoule opener when an ampoule exposes a sharp edge or shatters while being opened.

When beds are adsorbing in parallel and there is more flow restriction in one vessel than the others, the flow will automatically balance between the beds to achieve an equivalent pressure drop. If it is minor, then it is ordinarily not an issue. If the flow imbalance is large enough, early breakthrough on the vessel with the high flow rate (lowest pressure drop restriction) can occur. In order to better balance the flow rate between the vessels, feeds must be adjusted. This is normally done by adjusting (partially closing) valves, either manual shutoff valves or the valve travel of automatic valves. It can be a trial and error process to achieve balance so it should occur as a series of small adjustments until the operation noticeably improves. In cases where this is not possible, adjustment of the cycles and/or conditions may be possible to prevent breakthrough. When all else fails, the inlet feed rate must be reduced until breakthrough no longer occurs.

Beads are round and smooth, strong and durable, exhibiting low dusting characteristics and potential breakage. The spherical shape results in only compressive forces, while pellets (extrusions) undergo compression as well as tension, making breakage more likely. The ends of the pellets also have angled edges, making them subject to chipping and breakage. In addition, beads naturally dense load for optimum loading density without the use of dense phase loading equipment.

• Morphology of the silica particles; meaning bead shape
• Surface area: this is a function of particle- and pore size
• Surface functionalisation
• Particle size distribution in terms of range and actual distribution of particles within the range (D10/D50/D90)

Make sure all bed loading materials, supplies, equipment, and manpower are accounted for and ready to go ahead of the start date.Keep the sieve as dry as possible prior to loading by storing appropriately. In the field, stage the product for each bed so that all the materials to be loaded in a bed are present and ready to be loaded. Do not place packaging directly on the ground (keep on pallets) and cover with tarps when needed to keep packaging and the sieve dry. Maintained sealed packaging until time to loadinto the vessel or hopper (when applicable). Avoid loading in the rain whenever possible. Sieve readily adsorbs water from the air and the wetter the environment, the more water the sieve will adsorb during the loading.

DMSO-d6, Chloroform-D and Methanol-d4 are the most used solvents for NMR applications due to its wide range of solvent constraints as well as its simple spectrum and high boiling point.

Typically, there are some options that allow continued operation in the plant until a change out can occur. Adjustments to the cycle times, regeneration and feed conditions, and flowrates are sometimes available and can be made. The last thing considered is a reduction in the feed flow rate once all else has been done and further adjustment may be necessary. Zeochem can help with recommendations and a prioritized plan of action.

Purmol 3ST is available in 90kg drums, 105kg drums, 20kg valve sacks (600kg/pallet), 480kg big bags.Purmol 4ST is available in 20kg valve sacks (600kg/pallet).

Heavy water is a valuable material and should not be disposed. You can return your depleted heavy water to Zeochem. Please contact us at info@zeochem.com for more information.

Bead dusting and breakupis a common cause of pressure drop increase. This is often caused by upsets such as rapid pressure swings, liquids carryover, regeneration refluxing, and flow channeling. Rapid pressure swings can cause movement of the sieve orthe entire bed in some cases. When severe enough it can lead to flow channeling in the bed and early breakthrough in addition to increased pressure drop. Liquids carryover eventsin which liquids slam into the bed can cause sieve breakup, especially for repeated occurrence when it is a chronic problem. Regeneration refluxing occurs when liquids rain down on the sieve bed due to cooling and condensing at the top of the vessel early in the heating cycle while simultaneouslyliquids are being vaporized and driven from the sieve bed.It creates a rolling boil that can breakdown the sieve over time. In general, even under the best of circumstances, the pressure drop across the sieve bed normally goes up by 1.5-2 times over the life of the sieve due to bed settling and compaction, coke and carbon buildup on the sieve, anddust and particulate matter that collects in the bed.

Ordinarily the largest temperature swing occurs when a freshly regenerated sieve bed is placed back online. Although the bed has been cooled, it is often several degrees above the inlet feed temperature. As a result, a temperature bump of 15-20°F(8.3-11°C) often occurs, and lastsfor approximately 15-30 minutes after feed has been reintroduced to the bed. In addition, the adsorption process is exothermic, giving off heat. Normally the amount of contaminant being adsorbed is small enough to generate an increase in the product stream temperature of only2-4°F (1.1-2.2°C). Should anupset occur where a water spike or slug of water hits the bed, a much more pronounced temperature rise can result.

In general, higher sieve adsorption capacity is favored by lower temperature and higher pressure. This also help to lower the feed water concentration for water saturated applications. There is a balance to be maintained though in order to avoid approaching the hydrocarbon dewpoint in vapor phase systems. It is recommended to maintain operation at 10-20°F (5.5-11°C) above the dewpoint in order to avoid potential two phase flow. Mixed phase is always to be avoided given that adsorption and working capacity are negatively affected and can be unpredictable when this occurs. As a result, operation should always be 100% vapor phase or 100% liquid phase. For regeneration, lower pressure is favored for minimized flow rate and better turbulence, and lower temperature is favored for optimum sieve life. There are practical limitations and the heating temperature typically falls within a given range depending upon the type of sieve being used and the application details. Temperatures that are too low are too inefficient and may not remove enough contaminant; temperatures that are too high will cause accelerated coking and can cause decomposition of stream components. Pressure typically cannot be too low due to excessive velocity in the up flow direction that will cause bead movement; pressures that are too high require additional flow or time, and higher risk of regeneration refluxing and laminar flow.

• The larger the molecular weight of the target molecule to be separated the larger the pore size needs to be. The sample molecules need to be able to interact with the pores of the particle to create an efficient separation mechanism. If the pores are smaller than your target molecule it will not be retained and elute immediately.
• The larger the average pore size of the material the smaller will be the effective surface area. If you have less surface area available, your separation is generally less efficient. It is important to choose the right pore size for your target molecule.

A liquid slug can slam into the bed at high velocity, moving, displacing, and even crushing sieve beads. The liquid coats the sieve, slowing mass transfer which leads to poor adsorption of water and other contaminants, and adds more load to the regeneration step. Also, the liquid can cause accelerated coking during heating. To minimize coking, it is recommended to ramp heat at 100°F/hr (55.5°C/hr) when there is time to do so and in some cases an additional cool purge step for 30-60 minutes prior to heating is also recommended to help remove and strip out liquids prior to heating.

For short term shutdowns of less than 1 day, especially in warm climates, the vessels can be locked in under full pressure and simply restarted from the point of stoppage. In cold climates or wintertime conditions, 6-12 hours could be a downtime limitation due to more rapid cooling. In such cases, depressurizing or partial depressurizing of the vessels and surrounding piping and equipment would be recommended in order to avoid condensation and liquids during the shutdown. For upstream pipelines and equipment that cannot be depressurized, low point drains should be checked to make sure any collected liquids are drained off before restarting. For long term shutdowns of more than 1 day, it is recommended to regenerate all the beds first, depressurize down to 5-10 psig while maintaining a blanket of dry inert gas in each vessel. Check the vessel pressures periodically in order to maintain positive pressure to avoid air ingress. Note that any beds in a regeneration heating cycle should be completed prior to shutdown in order to avoid repeating the regeneration heating step from the beginning.

Excellent ZEOflair powder dispersion in the formula, choosing the correct ZEOflair powder type, and achieving the correct additivation (concentration) levels.

Purmol is an excellent moisture scavenger for polyurethanes, zinc rich primers, aluminum-pigmented coatings, and polysulfide systems.Purmol is also used in applications where sequestration of residual moisture is essential, such as warm edge spacers used in insulated glass and in packaging applications where even small amounts of moisture can degrade or shorten the shelf life of a product.

Purmol adsorbents are synthetic zeolites in powder form with a complex alkali aluminosilicate structure. This structure is very open in nature and contains pores of a regular and precisely defined size. This allows for a selective adsorption of molecules based on molecular size and polarity.

Purmol productsare manufactured at our production facility in Zvornik, Bosnia & Herzegovina.

The water capacity is the percent by weight that the sieve adsorbs. At equilibrium, the adsorption is basically driven to completion to determine the absolute maximum amount of potential adsorption. This is most often used as a general baseline measure of the sieve’s quality and ability to adsorb water. Dynamic capacity is the working capacity that is expected from the sieve to avoid breakthrough of water in an actual process. The design simulation determines this capacity based upon the feed and regeneration stream compositions and conditions, and the water concentration, as well as the concentration of other contaminants. It involves not only the equilibrium capacity, but calculation of the mass transfer zone, effects of other contaminants, andaging of the sieve over time. All of these factors contribute to the difference between achievable water adsorption in service and the theoretical maximum water loading for the sieve.

Zeochemproduces deuterium-labelled compounds. The enrichment is shown in percentage D (Deuterium). Chemical purity refers to the content of a particular substances. For NMR solvents, it is usually tested by GC in area percentage.

Purmol 3ST is a potassium (K) type A zeolite with a pore size of approximately 3 Ångstroms (0.32 nm).Purmol 4ST is a Sodium (Na) type A zeolite with a pore size of approximately 4 Ångstroms (0.4 nm).Both are excellent moisture scavengers, with Purmol 3ST being more exclusive to moisture adsorption.Purmol 4ST combines high adsorption capacity for water and slightly larger molecules, such as CO2 and smaller hydrocarbons.

The MOQ is 1x full pallet, 600kg (30x 20kg)

We recommend the use of glass ampoules. Each ampoule is sealed and inspected visually. We have ampoules in boxes of 10 with 0.5mL, 0.6mL, 0.75mL each available.

The D(50) for Purmol 4ST is 3.3um (D(90)=6.1um) The D(50) for Purmol 3ST is 3.5um (D(90)=6.0um)

When possible, first regenerate the sieve beds to ensure dryness. Normally a short 70-80% heating cycle is sufficient for this purpose given the sieve will not be as wet as during normal operation. If initial regeneration is not possible or if the sieve is loaded under sufficiently dryconditions, theunit can be started up on regular feed at 50% flow rate whilesimultaneously startinga regeneration cycle of 1 of the beds. As soon as the regeneration is completed, switch beds and start regeneration of another bed. Once all the beds have been regenerated, ramp up the feed rate to full design rate and adjust the cycles times to the technical recommendations.

Common upsets include feed water concentration spikes, pressure and temperature swings, flow changes or disruptions, changes in pressure drop, and operating control issues. It is recommended to immediately call ZeochemTechnical Service once the upset is discovered. After review of the details and the current operation, Zeochem will provide a technical assessment and makerecommendations to return the plant to normal operation. In many cases the unit can be lined out, however, sometimes the molecular sieve is damaged to the point where the adsorption capability is compromised. In these cases a reload of fresh sieve may be required. Our Technical Service team can help determine if that is necessary. It is also very important to identify the source and the cause of the upset so that measures can be taken to prevent it from happeningagain in the future.

Bonding different chemical groups onto the surface of bare silica results in functionalized silicas which give higherselectivity towards specific molecules.

• Bare/Silica has a high polar surface, it is the most popular stationary phase, ideal for conventional applications (normal phase separations, non-polar target molecules, pharmaceuticals, natural products)
• C4; suited to molecules with large hydrophobic regions, peptides, proteins. Usually combined with a large pore size for big biomolecules (>1000Da)
• PHE/phenyl; moderately nonpolar for aromatic compounds, aflatoxins, caffeine, phenols.
• C8; highly hydrophobic pesticides, peptides, drugs
• C18; more apolar than C8 and in reversed phase chromatography higher retention than C8. Has a non-polar surface, ideal for pharmaceuticals, steroids, fatty acids, peptides, proteins, pesticides, PCB’s
• Amino/NH2has a medium polar surface, ideal for carbohydrates and nitrogen containing heterocycles and amines. Scavenger applications.
• Diolhas a lesspolar surface (than bare silica) and still many hydroxy-groups, ideal for lipids; Our best option for many SFC applications.
• Cyano/CN unique selectivity for polar analytes with widely different chemistry eg. Cyclosporine, carbohydrates
• Thiol/SH; Mainly used for scavenging
• SCX/SO4^–:Ion Exchange for strong cation
• SAX/TMA; Ion exchange for weak anion
• NH2P; Ion exchange for scavenging

There are several advantages with use of 3A sieve that can potentially benefit the plant operation. 3A sieve is essentially a drop in replacement that gives the same or better performancethan 4A sieve in many applications. Only very small compounds such as ammonia and water easily pass through the 3A crystal pore openings for adsorption. If adsorption of other contaminants such as sulfur, CO2, and oxygenates is a concern, the 3A sieve minimizes co-adsorption of these compounds and helps maintain constant and stable levels of these contaminants in the product and regeneration streams, avoiding spikes and problematic levels. 3A sieve also regenerates more thoroughly at lower temperatureswith a typical target of 450°F (232°C). This saves energy and minimizes carbon laydown/coking. During each regeneration heating cycle, a small amount of carbon/coke is deposited on the sieve and over time, it causes adsorption capacity decline. Minimizing this thus helps to achieve longer sieve life.

• Irregular silica beads to be used in low -medium pressure systems
• Spheroidal Silica beads can be used in low to high pressure systems
• Spherical silica beads primarily used for high-resolution high-pressure systems

Where does water show up in NMR?

Zeochem offers a 3A molecular sieve powder Purmol 3ST as well as a 4A molecular sieve Purmol 4ST.

it depends on the size & concentration levels of odor/VOC compounds one tries to target for removal in the formulation. Type 100/110 for smaller size compounds, type 350 for medium size compounds, and type 800/810 for larger size compounds.

This depends on the type and size of oxygen concentrator, whether it is an existing design or new development, and other factors relating to the pressure swing adsorption design parameters. Zeochem’s technical sales team will be happy to assist with product selection to suit your particular needs.

Water reacts with active metallic pigments such as zinc or aluminum,forming hydrogen that leads toan overpressure in the cans

Zn + 2H2O → Zn(OH)2 + H2

2Al + 6H2O → 2Al(OH)3 + 3H2

Our molecular sieves may be added at any time during the blending of the primer by rapid stirring in conjunction with the addition of the zinc dust. Zeochem recommends the addition of 1% – 3% Purmol powder.

• Size and distribution of the silica particles effect the packing efficiency of the columns and therefore process performance.
• The higher the packing density, the higher the surface area, the more interaction between eluent and separation material resulting in higher efficiency separation. However, the higher the packing density, the smaller the mean particle size is and therefore the higher the backpressure will be.