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Catalyst Recovery Unique Porous Media Back to Oil Filtration

Industrial plant Process opertions involving catalysts have traditionally used leaf filters for catalyst recovery, and either bag filters or plate and frame filters for catalyst removal. Modern filter technology, utilizing sintered prorus metal tubes, provides superior filtration in both applications, and porous metal is now being specified in new construction and in the retrogit of existing systems. In addition to offering superior filtration, these porous metal filters reduce operator exposure to process materials, and reduce or eliminate disposal costs for spent filtration media.

Mott Corporation's HyPulse® LS Series filters have been applied extensively throughout the chemical and hydrocarbon processing industries for removal and recovery of supported precious metals and other valuable catalysts. Mott offers four HyPulse configurations, each designed for specific catalyst removal and recovery applications.

  • HyPulse LSI: Employs inside to outside flow path proven effective in high solids batch continuous operations where maximum filtrate recovery is required.
  • HyPulse LSM: Specifically applies to catalyst recovery processes with high specific gravity solids (such as RANEY® nickel). This highly versatile design can also be configured for close-coupled CSTR interface in a crossflow mode to maximize continuous product recovery during extended campaigns.
  • HyPulse LSP: Our conventional outside to inside configuration, ideally suited for low-solids polishing applications.
  • HyPulse LSX: Conventiional crossflow microfiltration applied when fine or attrited catalysts are present.

Advantages of HyPulse LSI filters in catalyst filtration - Mott Corporation recommends the HyPulse LSI filter configuration for most catalyst applications. The following is a brief description of distinct LSI benefits:

Superior Filtrate Quality.
  • Exceptional filtrate quality, with less than 1 ppm particulate. Mott porous metal filter elements are specifically engineered for complete particle removal.
  • Superior filtrate quality is achieved without the use of a precoat or a polishing filter.
Inner diagram of Mott LSI Filter Cycle and LSI Backwash Cycle

Filtrate and Catalyst Recovery.
  • 95-100% of the filtrate is recovered in each cycle. The amount of heel has been minimized in the unique LSI design.
  • 100% of the catalyst is recovered from the filter and can be returned to the reactor after each cycle. This is especially important when an expensive catalyst is used and when efficient catalyst recycle is required.

Closed System
  • The filtration system is sealed from operation exposure. The filter's clean operation and handling ease make it ideal for applications utilizing pyrophoric catalysts, dangerous chemicals, and / or solvents.
  • Mott HyPulse Filters can be put in line with the process steam. No feed tank is required for many applications.
Inherently more efficient than traditonal outside-in liquid-solids filters, Mott HyPulse LSI filters pass the slurry through the elements from the bottom-up and inside-out, resulting in less heel, minimal loss of filtrate, and easier discharge of solids.
  • A minimal amount of downtime and maintenance is required for operation. "Permanent" porous metal filter elements eliminate the need for frequent cartridge or bag replacement and disposal.
  • Filters have no moving parts.
  • Filters can be fully automated.

Inside-Out Filtration.

  • The HyPulse LSI eliminates traditional cake bridging and channel flow problems.
  • A smaller filter housing is required because elements are packed closer together.

Solids Discharge.

  • Solids can be removed from the filter as a low-solids slurry backwash or as a high-solids wet cake.

Wide Range of Materials.

  • Rigid Mott porous metal filter elements are available ina wide variety of materials. Standard elements are made of 316LSS. Optional materials include 304LSS, Inconel®, Monel®, Hastelloy®, Alloy 20, and titanium.

Long Product Life.

  • Long element life is ensured by correctly matching the type of porous media with a given catalyst and process liquid.
Mott HyPulse LSI catalyst filtration process.

A simplified installation schematic for the HyPulse LSI in a typical catalyst application is shown right.

A general description of a typical operation is as follows:

Slurry Backwash Recycle - Primary Catalyst Filter

  1. Valve (1) is opened. The reactor is pressurized to move the feed slurry.
  2. Valve (2) is opened. Solids collect on the inside of the porous elements while filtrate moves through an open valve (3) and is collected downstream.
  3. The filtratioin continues at a constant flow rate until the batch from the reactor is completely filtered.
  4. Valves (2) and (3) close. Backwash gas valve opens and housing is pressurized.
  5. Catalyst solids are discharged through valve (4) directly into the reactor using liquid and pressurized gas pulse.
  6. When the next reaction is completed, Step 1 is again initiated.
  7. This recycling system continues until the catalyst has lost activity and requires regeneration.
Slurry Backwash Flow Diagram

Removal of catalyst from the reactor system.

Many reactor systems require that a protion of the catalyst be replaced for each cycle. This illustration shows a typical HyPulse LSI catalyst filtration application.

Wet Cake Discharge - Solids Purge Filter.

  1. Filtration is the same as for the primary catalyst filter except that the feed slurry is periodically directed through valves (1), (5), and (6) to the solids purge filter.
  2. When the filtration is completed, the shell is drained and the cake is partially dried with gas pressure. Subsequently, the heel is drained from the filter.
  3. To discharge the wet cake, the filter is pressurized with blowdown gas and valve (7) is opened. The solids are discharged into a drum (which can be sent for regeneration).
  4. Catalyst is replaced from the catalyst make-up tank.
Slurry Backwash with Spent Catalyst Recovery Diagram

LSM Process Filter Inner Diagram
HyPulse LSM filters design versatility.

Mott's unique HyPulse LSM design incorporates all of the features available in the LSI design, with the added capability of introducing feed to the top of the filter. This feature eliminates the potential for classification of high-density solids which can occur in an upflow mode. As shown below, the patented LSM design utilizes "double openended" filter elements which allows for incorporation as crossflow filters into recirculating reactor loop systems.

LSM Filter Options Flowsheet

Inside-out filtration used in Mott HyPulse LSI and LSM filters results in more uniform deposition, and more secure retention of solids, while eliminating the problem of cake bridging between elements often associated with outside-in filtration.

Close-packed filter elements enable Mott to design compact LSI and LSM systems with more total filtration area than much larger competitive systems.

Mott Inside-Out Filtratiion and Outside-In Filtration Diagram

HyPulse LSP filters.

Mott can apply its conventional outside-inside flow configuration (HyPulse LSP) in cases where only trace quantities of solids are present (typically < 100 ppm). In these "polishing" applications, there is little concern for significant development of filter cake on the outer diameter of the elements, and element spacing is not as critical as is the case for most catalyst recovery operations.

Applies to polishing applications, the HyPulse LSP is designed with an economic, close-packed, removable filter element bundle. Backwash liquids from the LSP filter are usually pumped as low-solids slurries.

HyPulse LSX Filters
HyPulse LSX filters.

Some catalyst systems do not lend themselves to formation of permeable cake with good release characteristics upon backwashing. Mott may recommend HyPulse LSX crossflow filters in such cases. During operaiton of LSX, feed is pumped through the inner diameter of the LSX filter elements at velocities up to 20 ft/s. The turbulence developed at these velocities helps to continually remove particulate from the filter surface. Backpulsing or clean in-place procedures can be applied as needed.

Removal and recovery of heterogeneous catalysts represents the flagship application for Mott's HyPulse LS Series fiters. With numerous Fortune 500 repeat customers, Mott remains the preferred choice for state-of-the-art catalyst management and associated product yield.

Laboratory and design capabilities.

Microscopic evaluation in the lab - macroscopic evaluation in the field.

For through efvaluation of new applications, Mott maintains a Development and Testing Laboratory. Both scanning electron and optical microscopes, along with computer-controlled porometers, are used to inspect pore size, shape, and distrubution. Particle counters, particle-size analyzers and a fully instrumented test stand are used to evaluate performance.

  • Feedstock profiling
  • Filtration feasibility
  • Solids characterization
  • Material compatibility and selection
Often our laboratory evaluations provide a suitable basis for filter designs. If additional evaluations are recommended, Mott offers portable HyPulse filter systems that are fitted with the filter elements to be tested, and configured for the customer's application. After the system is transported to the testing site and installed, Mott engineers assist with start-up and data acquisition followed by scale-up.

Diagram of Inside-out Filtration
HyPulse LSI filters incorporate inside-out filtration, a method unique to Mott Corporation for removal / separation of a suspended material from a liquid. At the end of each filter cycle, solids are backwashed off the inside of the elements and discharged as a concentrated slurry or wet cake. This process not only allows an increase in filtration efficiency, but also prolongs the life of the elements. Distinct LSI benefits include:


The state-of-the-art porous metal elements of the HyPulse LSI offer the ultimate in particle retention, backwashability, solids capacity and strength. Media differential pressure can be as high as 125 psi. Standard elements are 316L stainless steel in normal particle retention ratings of 0.2 to 20 microns. Alternate metal materials are also available.


Mott HyPulse LSI filters typically yield filtrates with less than 1 ppm of suspended solids without the use of filter aids. The filtrate quality is consistent, cycle after cycle, due to Mott's superior media uniformity.

Process Flexibility

The unique inside-out design of the LSI filter produces a low heel and yields virtually 100% filtrate recovery.


The HyPulse LSI is designed so that it is sealed from operator exposure. Backwashing is accomplished internally through a controlled pneumatic / hydraulic pulse which uses fluid dynamics to rapidly dislodge the filter cake. The unique wet-cake discharge option removes solids without operator handling. The LSI meets OSHA requirements.


Rapid turnaround between cycles keeps the filter on line. Blowdown or backwash can be completed in less than five minutes. Element life is generally measured in terms of years.

Fully Automated Control

The Mott HyPulse LSI is available as a completely instrumented system for fully automated operation.

Ideal for Catalyst Recovery

High-solids holding capacity and high-efficiency solids removal make the LSI filter the first choice in catalyst recovery recycle applications. It has proven successful in removing catalyst material from aqueous slurries, fatty alcohols, edible oils and many other liquid filtration processes.

100% Catalyst Recovery

The HyPulse LSI's backwashing technique recovers and recycles virtually 100% of captured solids for consistent reaction cycles. Sincle vessel capacities of greater than 10 cubic feet of solids and lfow of over 200 gpm are available.

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