1) The following recipe is given for a zeolite. Determine the gel composition, express your
answer as ratio of oxides in the gel, where the basis is Al2O3. For a neutral template
species, use just the mole ratio of this species to alumina. Percentages below are wt. %
unless otherwise indicated
Material Quantity (g) Comments
Distilled water 290
Sodium hydroxide 6.0 50 % aqueous solution
Sodium aluminate 21.5 46 % Al2O3, 31% Na2O, remainder water
Silica Sol 57.0 Dupont Ludox AS-40, 40% SiO2
292 N(CH3)4ꞏOH 25% aqueous
3) The nitrogen isotherm isotherm below was collected for a mesoporous material.
Answer the questions below regarding isotherm and what you can deduct from it.
0 0.2 0.4 0.6 0.8 1
P / Po
a) Identify the IUPAC type isotherm. Be as specific as possible (e.g. subcategories)
b) Identify (circle on the graph or give range) the subset of the data used to calculate the
sample surface area.
c) Identify (label on the graph) the adsorption and desorption branches of the isotherm
d) At gas uptake approaching P/P0 = 1, the isotherm takes a little uptick. What might you
attribute this feature to?
e) What is the approximate total pore volume (micropore + mesopore) for this sample?
The volume given in the graph is the gas uptake at STP (1 atm, 273.15 K), and you may
assume the liquid density of N2 at 77K is 0.807 g/cm3. Show your work for full credit.
6) a) Ammonia has recently been shown to be a significant point source pollution problem,
and you wish to kinetically separate NH3 from air. Which of the following structures
and Si/Al combinations would you test first? You may change cations as you see fit.
Check 3 of the 11 listed.
CHA 2:1 CHA 13:1
ANA 2:1 LTL 1:1
MFI 10:1 SOD 1:1
FAU 1.5:1 MOR 4:1
RHO 3:1 GIS 1:1
AEI Al/P = 1:1
b) Add one more appropriate structure and Si/Al (Al/P) to the table above.
7) Match the zeolite to the most appropriate application
USY (FAU) Ion exchange
Linde A (LTA) Emission control (de-NOx)
Na-X (FAU) Dehydration, gas drying
ZSM-5 MFI) Catalytic cracking
Beta (BEA) Hydrocarbon processing, isomerization, cracking,
Silicalite-1 (MFI) Hydrocarbon adsorption
SSZ-13 (CHA) Gas Separation
9) The ternary diagram (adapted from Breck) below depicts the products observed for
varying gel compositions in the Na2O : SiO2: Al2O3 : H2O system. Experimental
conditions were crystallization temperature was 100°C, sodium silicate was the silica
source, and the water content is 90-98 mol %.
a) Why are all the identified structures in the left side of the diagram?
An artifact of Lowenstein’s Rule
There are insufficient Na+ ions to counteract Al+3 as a Tatom,
therefore the alumina precipitates in octahedral
coordination. No zeolite is formed.
It’s an artifact of the experimental design, Breck and coworkers
did not investigate that space
There are insufficient OH- to fully mineralize the silica in
the right half of the diagram
11) Two questions with same answer key:
a) Which of the following post-synthesis treatments will be most effective against
significant coke formation?
b) Which of the following post-synthesis treatments will be most effective at reducing
unwanted octahedral alumina?
Sialylation by chemical vapor deposition (CVD) with SiCl4
Acid washing with HCl
EDTA treatment (EDTA = ethylenediaminetetraacetic acid)
A combination of mild steaming followed by acid washing
12) You discover a new low SAR, 8-ring structure. You will experiment with different
cation forms for this structure. Based on your knowledge of similar structures, you
expect the pore openings for kinetic gas separation will progress as follows (answer all
Fastest / largest opening → Slowest / smallest opening
Li+ > Na+ > K+
Na+ > K+ > Ca++
Ca++ > Na+ > K+
Li+ ≈ Ca++ > K+
K+ ≈ Li+ > Ca++
Ca++ > K+ > Na+
13) Within one framework structure, increasing the Si/ Al ratio will (check all that apply)
Increase the number of acid sites
Increase acid site strength
Increase stability in caustic
Increase stability in acidic media
Increase hydrothermal stability
Increase the T-atom density
Increase the ion exchange capacity.
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