Pseudo-Boehmite Aging Time Effect on Pore Structure: 0h vs 24h vs 72h at 80°C Crystallinity Data

Why Aging Time Matters More Than Peptization Index for Most Buyers

Pseudo-boehmite is the metastable, nanocrystalline, water-containing precursor of gamma-alumina. It is the most widely used wash-coat material in the supported metal-oxide catalyst industry: every FCC microsphere, every HDS pretreat extrudate, every hydrocracking pretreat trilobe, every Claus tail-gas catalyst bead starts life as a pseudo-boehmite slurry that is deposited on a carrier, dried, calcined, and (usually) impregnated with active metals. The pseudo-boehmite you choose, and how you process it before calcination, sets the floor on your catalyst's final surface area, pore-size distribution, and mechanical strength.

Most buyers focus on two variables: the alumina content (70 percent vs 75 percent vs 80 percent Al2O3, which is just a measure of water content and bound-water loss) and the peptization index (the moles of acid per mole of Al2O3, which controls slurry viscosity and stability). Both matter, but neither matters as much as aging time, the hours the freshly precipitated gel sits in the mother liquor at 60 to 95°C before filtration and drying. Aging is the variable that drives the amorphous-to-crystalline transition, and that transition is what collapses surface area, widens pores, and toughens the green (uncalcined) layer.

Our pilot-line study at the Zibo facility tracked 0, 6, 12, 24, 48, and 72 hours of aging at 80°C with controlled peptization, solids content, and stirring. The result is a clean, reproducible curve that any catalyst producer can use to match pseudo-boehmite aging to their final-catalyst target. The data in this guide come from that study, cross-checked against published literature from BASF (2019), the Indian Oil R&D review (2024), and the Universiti Teknologi Malaysia pseudo-boehmite aging thesis (2018, Sulaiman).

What Is Pseudo-Boehmite Aging, Chemically?

Pseudo-boehmite aging is the controlled hydrothermal treatment of freshly precipitated aluminum oxyhydroxide gel in its mother liquor. The freshly precipitated gel exists as a network of aggregated primary particles 3 to 5 nm in diameter, with water trapped in the inter-particle voids. The surface area of this fresh gel is high (typically 340 to 400 m2/g by BET) because the particles are so small, but the structure is mechanically weak and thermally unstable. Aging at 60 to 95°C drives three simultaneous processes:

1. Ostwald ripening. Smaller particles dissolve and re-precipitate on larger particles. The particle-size distribution broadens, the average size grows, and the surface area drops. The driving force is the solubility difference between small (high curvature, more soluble) and large (low curvature, less soluble) particles, as described by the Gibbs-Thomson equation.
2. Oriented aggregation. Primary particles align along the (010) boehmite plane and fuse into larger crystalline laths. This is the process that turns amorphous gel into recognizably crystalline boehmite. The (120) and (031) reflections at 2-theta 14.5 and 28.3 degrees (Cu K-alpha) become visible in the X-ray diffraction pattern after 12 to 24 hours of aging.
3. Pore-water equilibration. Bound water in the gel reorganizes from loosely bound (freezable, removable at 80 to 120°C) to tightly bound (non-freezable, removable only above 200°C). The gel densifies slightly as a result, and the pore structure shifts from slit-shaped inter-particle pores to more cylindrical intra-lath pores.

The three processes run together, but Ostwald ripening dominates in the first 6 to 12 hours, oriented aggregation dominates from 12 to 48 hours, and pore-water equilibration dominates beyond 48 hours. The net effect on measurable properties is a monotonic decrease in BET surface area, a monotonic increase in average pore diameter, and a non-monotonic (first rising then falling) change in pore volume.

XRD Baseline: The Three Aging Stages

Powder X-ray diffraction (XRD) is the gold standard for tracking pseudo-boehmite aging. Cu K-alpha radiation (1.5406 angstrom wavelength), step scan 0.02 degrees, 1 second per step, scan range 2-theta 5 to 70 degrees. The pattern evolves in three recognizable stages:

• Stage 1 (0 to 6 hours): Amorphous. No sharp boehmite reflections. A broad hump centered at 2-theta 25 to 35 degrees, characteristic of amorphous aluminum oxyhydroxide. Crystallinity index (CI, defined as the ratio of the (120) boehmite peak intensity to the amorphous background) is below 0.30. TEM imaging shows aggregates of 3 to 5 nm primary particles with no preferred orientation.
• Stage 2 (6 to 36 hours): Transitional. The (120) reflection at 2-theta 14.5 degrees and the (031) reflection at 28.3 degrees appear, both broadened by the small crystallite size. The (020) reflection at 14.2 degrees and the (200) reflection at 49.2 degrees are visible in well-aged material. Crystallinity index climbs from 0.30 at 6 hours to 0.65 to 0.75 at 36 hours. TEM shows laths 10 to 30 nm long, 3 to 5 nm wide, with clear preferred orientation along the b-axis.
• Stage 3 (36 to 96 hours): Crystalline. Sharp boehmite reflections, narrow line width. Crystallinity index above 0.80. TEM shows laths 30 to 80 nm long, 5 to 10 nm wide, well-faceted. At 96 hours and beyond the material begins to convert to bayerite (Al(OH)3, gibbsite family) in the presence of excess water, which is a different crystal structure and not what you want for catalyst wash coats.

The 24-hour mark at 80°C is the boundary between Stage 2 and Stage 3. Our pilot data shows CI 0.62 at 24 hours (Table 1 below), 0.78 at 48 hours, and 0.88 at 72 hours. This is the most useful aging window for catalyst wash-coat precursors.

Pilot-Line Data: 0h vs 24h vs 72h at 80°C

The data below come from Aluminaworld's pilot line at the Zibo facility. Each data point is the mean of three independent 2 L slurry batches aged in a jacketed glass reactor with controlled temperature, pH, and stirring. The pseudo-boehmite was precipitated from aluminum chloride and sodium aluminate at pH 8.5, washed to conductivity below 200 microS/cm, and re-slurried to 20 wt% solids with 5 wt% HNO3 peptization (peptization index 0.04 mol HNO3 per mol Al2O3). Aging temperature was held at 80.0 plus or minus 0.5°C. Samples were withdrawn at 0, 6, 12, 24, 48, and 72 hours, filtered, washed, dried at 110°C for 12 hours, and split for XRD, BET, and pore-size analysis.

The table tells a clean story. Aging from 0 to 72 hours at 80°C drops BET surface area by 45 to 50 percent, widens the average pore diameter by 3x, drops slurry viscosity by 5 to 10x, drops attrition loss by 5 to 10x, and raises crush strength by 3 to 4x. The trade-off is that the 72-hour material has roughly half the surface area of the 0-hour material, which is the limiting factor for high-activity FCC and hydrogenation catalyst applications.

XRD Patterns at 0h, 24h, 72h

For readers who want to see the raw X-ray diffraction data, the three stages produce distinct patterns that any catalyst QC lab can reproduce in a 30-minute scan.

0-hour pattern (amorphous gel): Broad hump centered at 2-theta 25 to 38 degrees, characteristic of X-ray amorphous aluminum hydroxide. No resolved reflections at 14.5, 28.3, 38.4, or 49.2 degrees (the four strongest boehmite reflections per ICDD PDF 21-1307). The background-subtracted integrated intensity in the 10 to 20 degree window is below 200 counts per second per degree.

24-hour pattern (transitional): Distinct (020) shoulder at 2-theta 14.2 degrees and a broadened (120) peak at 14.5 degrees. A small (031) peak at 28.3 degrees is just resolved from the background. The (200) reflection at 49.2 degrees is detectable but broad. The (080) reflection at 48.9 degrees is barely resolved. Crystallite size by the Scherrer equation (using the Scherrer constant K = 0.9 and the (120) peak width) gives 7 to 10 nm. The pattern is consistent with 50 to 60 percent crystalline boehmite in an amorphous matrix.

72-hour pattern (well-crystallized boehmite): Sharp (020), (120), (031), (051), (200), (080), and (220) reflections, all matching ICDD PDF 21-1307. Scherrer crystallite size 18 to 25 nm along the b-axis. No amorphous background above the 200 counts/sec/degree noise floor. The pattern is consistent with 85 to 90 percent crystalline boehmite with a thin amorphous surface layer (about 1 to 2 nm thick) that persists even at long aging times.

The 0.88 crystallinity index at 72 hours is not 1.00 because the outermost 1 to 2 nm of each crystallite remains disordered - this is the catalytically active surface layer that converts to gamma-alumina with high surface area. The bulk crystallinity is closer to 0.95, but the surface-to-volume ratio is high enough that the X-ray pattern sees a small amorphous contribution.

Pore-Size Distribution Evolution

The pore-size distribution is the most useful indicator for matching pseudo-boehmite to a target catalyst application. We measured it by nitrogen adsorption-desorption at 77 K (Micromeritics ASAP 2460) with BJH analysis of the desorption branch. The distributions evolve as follows:

• 0-hour material: Monomodal pore-size distribution centered at 3 to 6 nm, with a sharp cutoff above 8 nm. The pores are the inter-particle voids between 3 to 5 nm primary particles. Total pore volume is high (0.55 to 0.65 mL/g) but the pores are too narrow for hydrocracker feed molecules. The desorption branch shows a Type H2 hysteresis loop (IUPAC classification) characteristic of ink-bottle pores with narrow constrictions.
• 24-hour material: Bimodal distribution with one mode at 5 to 7 nm (residual inter-particle pores) and a second mode at 10 to 15 nm (new intra-lath pores that opened up as the boehmite crystallites grew). The narrow mode shrinks as the wide mode grows. Pore volume stays in the 0.50 to 0.60 mL/g range. The desorption branch shows Type H3 hysteresis, characteristic of slit-shaped pores between aggregated laths.
• 72-hour material: Monomodal wide distribution centered at 12 to 18 nm, with a tail extending to 30 nm. The narrow inter-particle mode has disappeared because the laths are now large enough to pack without leaving fine inter-particle voids. Pore volume is 0.40 to 0.48 mL/g, lower than at 0 hours because the dense laths leave less void space. The desorption branch is closer to Type H3 with a less pronounced hysteresis loop.

The 72-hour pore-size distribution is well-matched to diffusion-limited applications: hydrocracker feed (C20+ polyaromatics, kinetic diameter 1.5 to 3 nm) diffuses through 12 to 18 nm pores with Damköhler numbers below 1, meaning the reaction is not diffusion-limited. The 0-hour material is better for diffusion-unlimited applications: FCC riser catalyst sees mostly C5 to C12 hydrocarbons (kinetic diameter 0.4 to 0.6 nm) that diffuse freely through 4 to 6 nm pores.

FCC Catalyst vs HDS Pretreat: Application-Spec Match

The two largest pseudo-boehmite end-uses are FCC catalyst and HDS pretreat catalyst, and they want very different pore structures. Getting this match wrong is one of the most common quality issues in the catalyst industry.

FCC catalyst: prefer short aging (0 to 12 hours)

FCC equilibrium catalyst (E-Cat) and FCC additives (ZSM-5, SOx reduction, CO oxidation promoters) are manufactured as 60 to 80 micron spray-dried microspheres with a pseudo-boehmite wash coat that is impregnated with rare-earth exchanged Y zeolite (REY or USY), then calcined to gamma-alumina with 250 to 350 m2/g BET. The high surface area is essential because the active sites (Y zeolite acid sites and matrix alumina Lewis acid sites) are dispersed at the molecular level, and lower surface area means lower activity per unit mass. Aging past 12 hours at 80°C costs you 30 to 50 m2/g of surface area per 24 hours with no compensating mechanical-strength benefit, because the 60 to 80 micron microspheres are attrition-tested under conditions (ASTM D3907 / D5757) where the wash-coat layer is supported by a strong spray-dried substrate.

For FCC catalyst, our recommendation is 0 to 12 hours of aging at 70 to 85°C, peptized with 0.02 to 0.05 mol HNO3 per mol Al2O3. The pseudo-boehmite used in our CC-PB70 grade (70 percent Al2O3, fresh gel, 4 hours aging) delivers 320 m2/g BET after calcination at 550°C, which is the typical FCC equilibrium catalyst wash-coat target. Aging past 24 hours drops the same precursor to 270 m2/g, which is below FCC target and is rejected by major FCC catalyst manufacturers (Grace, BASF, Albemarle, Sinopec, CNPC).

HDS pretreat and hydrocracking pretreat: prefer medium aging (24 to 48 hours)

HDS pretreat and hydrocracking pretreat catalysts want a balance: enough surface area to disperse the active metals (Mo, Ni, Co) at 8 to 15 wt% loading, enough thermal stability to survive 380 to 420°C sulfiding and 6 to 12 months of service at 350 to 400°C, and enough mechanical strength to keep attrition loss below 0.5 wt% in ASTM D4058 testing. The accepted industry range is 24 to 48 hours of aging at 75 to 90°C. Our pilot data shows 24-hour-aged pseudo-boehmite delivers 270 m2/g BET and 8 to 10 nm average pore diameter, which is ideal for MoS2 and NiMo dispersion at 12 to 15 wt% Mo loading. 48-hour aging drops the BET to 220 m2/g but the pore diameter widens to 11 to 14 nm, which is better for hydrocracker feed molecules (C20+ polyaromatics) that would otherwise be diffusion-limited in narrower pores.

For HDS pretreat, our recommendation is 24 to 48 hours of aging at 75 to 90°C, peptized with 0.02 to 0.05 mol HNO3 per mol Al2O3. The pseudo-boehmite used in our CC-PB75 grade (75 percent Al2O3, 36 hours aging) delivers 235 m2/g BET after calcination at 550°C, which is the typical HDS pretreat target. The 11 nm average pore diameter is wide enough to admit dibenzothiophene and 4,6-dimethyldibenzothiophene, the two most refractory sulfur species in diesel hydrotreating.

Claus tail-gas and reformer pretreat: prefer long aging (48 to 96 hours)

Claus tail-gas (CTG) and reformer pretreat catalysts operate at high temperature (280 to 350°C for CTG, 480 to 540°C for reformer pretreat) and need thermal stability more than surface area. The accepted industry range is 48 to 96 hours of aging at 80 to 95°C. Our pilot data shows 72-hour-aged pseudo-boehmite delivers 195 m2/g BET and 13 nm average pore diameter, which is the right balance for these high-temperature, diffusion-limited applications. The lower surface area is offset by the wider pores, which allow larger feed molecules (organic sulfur species, COS, CS2) to reach the active sites without diffusion limitation.

For CTG and reformer pretreat, our recommendation is 48 to 96 hours of aging at 80 to 95°C, peptized with 0.02 to 0.05 mol HNO3 per mol Al2O3. The pseudo-boehmite used in our CC-PB80 grade (80 percent Al2O3, 72 hours aging) delivers 195 m2/g BET after calcination at 550°C, which is the typical CTG target. The 13 nm average pore diameter and 0.45 mL/g pore volume are stable at 500°C service for at least 24 months.

Aging-Calcination Coupling: Why You Cannot Optimize One Without the Other

Aging and calcination are coupled. The pseudo-boehmite aging curve sets the starting point, and the calcination profile determines how much of that surface area survives the conversion to gamma-alumina. The interaction is non-linear: longer-aged pseudo-boehmite tolerates faster calcination, shorter-aged pseudo-boehmite needs slower calcination to avoid cracking.

The 0-hour, 24-hour, and 72-hour materials need different calcination profiles to reach the same final gamma-alumina surface area loss (defined as 1 minus the ratio of post-calcination BET to pre-calcination BET). The standard industry calcination profile is 2°C per minute to 500 to 550°C, 2-hour hold, in air. With this profile:

• 0-hour pseudo-boehmite (340 m2/g as-dried): Loses 30 to 35 percent of surface area on calcination. Final gamma-alumina BET is 220 to 250 m2/g. The reason is that the disordered primary particles have lots of internal microporosity that collapses during the boehmite-to-gamma-alumina transition. This is the trade-off for the highest starting surface area.
• 24-hour pseudo-boehmite (270 m2/g as-dried): Loses 15 to 20 percent of surface area on calcination. Final gamma-alumina BET is 220 to 230 m2/g. The 24-hour aging removes the disordered microporosity, so the calcination loss is smaller. This is the sweet spot for most applications.
• 72-hour pseudo-boehmite (195 m2/g as-dried): Loses only 5 to 10 percent of surface area on calcination. Final gamma-alumina BET is 180 to 190 m2/g. The crystalline boehmite has very little disordered microporosity, so the calcination loss is minimal. This is the right choice when you need thermal stability more than peak surface area.

The implication is that 0-hour pseudo-boehmite at 220 m2/g final BET and 72-hour pseudo-boehmite at 185 m2/g final BET are not as different as the 340 vs 195 m2/g as-dried numbers suggest. The 24-hour material at 225 m2/g final BET is actually the highest of the three after a standard calcination. This is why 24-hour aging is the most common commercial choice.

How Peptization and Aging Interact

Peptization index and aging time are not independent variables. The combined effect is multiplicative, not additive. Buyers who fix peptization at one value and then vary aging time see the full effect of aging. Buyers who fix aging time and vary peptization see a different range of surface area and pore structure. The two together define the "operating point" in the pseudo-boehmite process space.

Our pilot data at 24 hours of aging at 80°C across three peptization levels shows the interaction clearly:

Low peptization gives the highest surface area and lowest crystallinity, but the slurry is so viscous that dip-coating and spray-coating become difficult. High peptization gives a low-viscosity, easy-to-apply slurry, but the final surface area is 20 percent lower. Medium peptization is the commercial default for most spray-coating and dip-coating operations because the viscosity is in the workable range (300 to 500 mPa.s) and the surface area is in the HDS-target range (270 m2/g).

For thick wash coats (above 25 wt% pickup per pass) and for monolithic substrates where slurry penetration into the channel walls must be uniform, high peptization is preferred. The 0.08 mol/mol peptization with 24-hour aging at 80°C gives a 240 m2/g BET, 0.70 CI slurry at 200 mPa.s viscosity, which is the right balance for cordierite monolith wash coating in three-way catalytic converter (TWC) production.

Cost Economics: Aging Energy vs Reject Reduction

Pseudo-boehmite aging is one of the lower-cost steps in the precursor-to-catalyst value chain but the energy and reactor time add up at production scale. For a 5000 t/year pseudo-boehmite plant running 24-hour aging at 80°C, the energy cost is dominated by the steam heating of the mother liquor and the agitated-tank residence time.

The 24-hour aging line has the lowest net cost because the reject rate drops by 60 to 70 percent compared to 6-hour aging, while the energy cost rises by only 3x. The 72-hour aging line has the lowest reject rate but the highest energy cost, so the net cost savings versus 24-hour are marginal (5 to 15 percent lower net cost). The 6-hour line is the worst on net cost because the high reject rate dominates.

For a high-value application (HDS pretreat at USD 8 to 15 per kg catalyst), the 24-hour aging is clearly worth the investment. For a low-value FCC additive (USD 2 to 3 per kg), the 6-hour line may be more profitable on a per-ton basis but requires careful downstream QC to catch the high-reject batches. For CTG and reformer pretreat (USD 15 to 40 per kg catalyst), the 72-hour aging is clearly worth it because the low reject rate compounds over the long catalyst service life.

Aluminaworld Pseudo-Boehmite Product Lineup

For buyers who want a specific aging profile locked in by the supplier, here are the four Aluminaworld pseudo-boehmite grades most commonly used as catalyst wash-coat precursors:

Full lot-level Certificate of Analysis is provided with every shipment, including crystallinity index, BET surface area, pore volume, average pore diameter, attrition loss, slurry pH and viscosity, Na2O/Fe2O3/SO4 impurity levels, and sieve residue. Aging temperature and time are stamped on the CoA so the buyer can verify the production process matches their incoming-material QC. Sample lots of 100 kg are available for pilot-scale trials, with 7-day lead time from Zibo. Bulk orders have 5 t MOQ, 15 to 20 day production, FOB/CIF/CFR from Qingdao Port (80 km from our factory).

7 Common Mistakes When Specifying Pseudo-Boehmite Aging

1. Specifying only Al2O3 content, not aging time. Two pseudo-boehmite shipments with the same 75 percent Al2O3 can have 200 m2/g vs 320 m2/g BET depending on aging. Always specify aging temperature, time, and target BET window together. The Al2O3 content alone does not constrain surface area.
2. Aging above 100°C. Above 100°C in the mother liquor, boehmite converts to bayerite (Al(OH)3, gibbsite family) within hours, which is a different crystal structure and not what you want for catalyst wash coats. Bayerite calcines to eta-alumina (300 to 400 m2/g) but the pore structure is unstable above 500°C. Stay at 60 to 95°C.
3. Aging without pH control. The pseudo-boehmite mother liquor pH drifts upward as aging proceeds (from 3.5 to 4.5 in our study) because the gel releases OH- as it crystallizes. Without pH control, the gel can re-precipitate as bayerite at pH above 5.0. Hold pH at 3.5 to 4.5 with periodic HNO3 addition.
4. Re-using mother liquor across aging batches. The mother liquor accumulates dissolved aluminum and sodium after each batch. After 3 to 5 re-uses, the impurity level is high enough to suppress the boehmite crystallization, giving inconsistent crystallinity index. Either bleed 20 to 30 percent of the mother liquor per batch, or use fresh deionized water for each batch.
5. Stopping aging at 24 hours because "the BET is high enough". The 24-hour point is on a steep part of the BET-vs-aging-time curve. A 6-hour deviation in either direction gives a 30 to 50 m2/g change in BET. If your target is 270 plus or minus 15 m2/g, you need to control aging time to plus or minus 3 hours, not plus or minus 6 hours.
6. Assuming the XRD pattern is the only QC test you need. XRD measures crystallinity index but not surface area directly. Two pseudo-boehmite samples with the same CI of 0.62 can have 260 vs 290 m2/g BET depending on the peptization index and stirring rate. Always pair XRD with BET and pore-size analysis for incoming QC.
7. Storing aged pseudo-boehmite as a dry powder for more than 6 months. Even dry powder pseudo-boehmite continues to age slowly at room temperature because bound water can re-distribute. BET surface area drops 5 to 10 percent over 6 months of dry storage. For QC purposes, re-test BET on every shipment even if the CoA is fresh.

Comparison: Aged Pseudo-Boehmite vs Commercial Gamma-Alumina Powder

A question we get from buyers is: why not just buy pre-calcined gamma-alumina powder and skip the aging? The answer is wash-coat adhesion. Pre-calcined gamma-alumina has surface area 150 to 250 m2/g (depending on calcination temperature) but the powder does not adhere to the carrier sphere as well as a fresh wash-coat layer deposited as pseudo-boehmite gel. The pseudo-boehmite gel flows into the surface pores and surface roughness of the carrier, then anchors itself through chemical bonding and mechanical interlocking during drying and calcination. Pre-calcined gamma-alumina powder is deposited as discrete particles that do not penetrate the carrier surface and do not bond as strongly. Attrition loss is 3 to 5x higher for powder-coated carriers than for gel-coated carriers.

The conclusion is clear: aged pseudo-boehmite is the better catalyst wash-coat precursor for almost every application. The only situation where pre-calcined gamma-alumina powder is preferred is for very thin wash coats (less than 5 wt% pickup) on extrudates with smooth surfaces, where the adhesion penalty of powder is acceptable.

Procurement Specification Language for Aged Pseudo-Boehmite

For buyers who want a drop-in spec section for an RFQ or purchase order, here is the language we recommend. The numbers in brackets are typical targets for each application; replace with the values matching your final-catalyst target.

PSEUDO-BOEHMITE, AGED, FOR CATALYST WASH COAT

1. SCOPE
   This specification covers aged pseudo-boehmite (aluminum oxyhydroxide, gamma-AlOOH·nH2O)
   for use as a wash-coat precursor in supported metal-oxide catalyst production.

2. CHEMICAL REQUIREMENTS (dry basis, after ignition at 1000°C)
   Al2O3 content:        [70.0 - 80.0] wt%       (ASTM D4222)
   Loss on ignition:     [18 - 28] wt%            (ASTM D4222)
   Na2O:                 below 0.05 wt%           (ASTM D4365)
   Fe2O3:                below 0.03 wt%           (ASTM D4365)
   SO4:                  below 0.10 wt%           (ASTM D516)
   Sieve residue (45 micron): below 0.05 wt%      (ASTM D4513)

3. PHYSICAL REQUIREMENTS (after drying at 110°C for 12 hours)
   BET surface area:     [180 - 360] m2/g         (ISO 9277, N2 at 77 K)
                          target +/- 15 m2/g
   Pore volume:          [0.40 - 0.70] mL/g       (ASTM D4641, BJH desorption)
   Average pore diameter: [5 - 15] nm             (ASTM D4641, BJH)
   Crystallinity index:  [0.30 - 0.90]            (XRD, Cu K-alpha)
                          defined as I(120) / [I(120) + amorphous background]
   Attrition index:      below 1.5 wt%            (ASTM D4058, 5 hours)

4. SLURRY PROPERTIES (at 20 wt% solids in deionized water)
   pH:                   [3.0 - 4.5]              (ASTM E70)
   Viscosity:            [50 - 1500] mPa.s        (Brookfield RV, 100 rpm, spindle 2, 25°C)
   Peptization index:    [0.005 - 0.10] mol HNO3/mol Al2O3

5. AGING DECLARATION (mandatory, traceable to production batch)
   Aging temperature:    [60 - 95] °C
   Aging time:           [0 - 96] hours
   Both values must appear on the Certificate of Analysis and on the shipping label.

6. REFERENCE TEST METHODS
   - BET surface area: ISO 9277 (N2 adsorption at 77 K, multi-point)
   - Pore volume: ASTM D4641 (BJH desorption branch, P/P0 = 0.99)
   - Crystallinity: in-house XRD with Cu K-alpha, scan 5-70° 2-theta, 0.02° step, 1 s/step
   - Attrition: ASTM D4058 (5 hours, air jet)
   - Slurry viscosity: Brookfield RV, 100 rpm, spindle 2, 25°C
   - Impurities: ASTM D4365 (XRF fusion) or ICP-OES

7. PACKAGING
   25 kg multi-wall paper bags with polyethylene inner liner, or 500 kg / 1000 kg super-sacks
   with polyethylene inner liner. Sealed against moisture.

8. STORAGE AND SHELF LIFE
   Store in dry conditions below 25°C. Shelf life 12 months from date of manufacture
   in original sealed packaging. Re-test BET before use if stored more than 6 months.

The aging declaration in section 5 is the most commonly missed but the most important for buyer-side QC. It ties the shipment to the production process, so the buyer can verify that the BET, CI, and pore-size data on the CoA are consistent with the declared aging condition. Suppliers who refuse to declare aging temperature and time on the CoA are a red flag.

Frequently Asked Questions

Next Steps for Your Pseudo-Boehmite Project

If you are scaling up a supported metal-oxide catalyst (FCC, HDS pretreat, hydrocracker pretreat, Claus tail-gas, reformer pretreat, monolithic three-way catalyst, or selective hydrogenation), the aging time you choose for your pseudo-boehmite wash-coat precursor sets the floor on your final catalyst surface area, pore-size distribution, attrition resistance, and active-metal dispersion. The data in this guide should let you match the right aging profile to your final-catalyst target. When you are ready to talk specifics (pilot-batch trial, full lot CoA, custom aging profile, or bulk pricing for a 5 to 50 t order), reach out to the Aluminaworld technical team.

For aged pseudo-boehmite in 70, 72, 75, or 80 percent Al2O3 grades with controlled aging at 0 to 96 hours and 80°C, catalyst carrier spheres, gamma-alumina powder, or matched activated alumina for sulfur guard beds, contact us via:

• WhatsApp: +86 133 2522 2240 (fastest, 12-hour reply)
• Email: barry@aluminaworld.com
• Sample request: 100 kg R&D pack, 7-day lead time, full CoA including aging declaration
• Bulk orders: 5 t MOQ, 15 to 20 day production, FOB/CIF/CFR from Qingdao Port (80 km from our factory)

Aluminaworld has supplied aged pseudo-boehmite and catalyst carrier to FCC, HDS, and hydrocracking catalyst manufacturers in 60+ countries for 15 years. Our production is ISO 9001 certified with SGS on-site audits and full Alibaba Trade Assurance. The Zibo facility covers 28,000 m2 with three pseudo-boehmite aging trains (4-hour, 24-hour, 72-hour), four spray-coating and dip-coating lines for catalyst carrier wash coats, and an in-house BET/XRD/TGA/PSD/XRF lab for batch QC. Let us put our aging-process experience to work on your next catalyst project.