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CHM181 > S19-S21 > Flashcards

S19-S21 Flashcards

1
Q

What are SOLID ACID CATALYSTS

A

are a subtype of heterogeneous catalysts employed in acid-catalyzed reactions
Solids that possess acidic properties on their surfaces function as catalysts just like liquid acids.
More environmentally friendly

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2
Q

HISTORICAL DEVELOPMENTS OF SOLID ACID CATALYSTS

A

Discovery of acidic properties (1902):
Kobayashi identified acidic properties in kambara earth, later named “acid earth.”
Applied in hydrocarbon production and oil processing

Houdry’s breakthrough (1930s):
Houdry developed a synthetic cracking catalyst, “silica–alumina.”
Shift from coal to petroleum-based due to increased gasoline demand

Evolution of reactor technology (1940s):
Introduction of fluid catalytic cracking (fcc) in 1942 for more efficient catalyst regeneration

Advancements with zeolites (1957-1961):
Zeolites (x and y) demonstrated superior activity in hydrocarbon reactions
Mobil researchers highlighted ca-x zeolite’s excellent cracking activity in 1961

Introduction of riser reactor (1960s):
Riser reactor introduced in the 1960s, utilizing high zeolite activity
Faujasite-type zeolites, with modifications, remain crucial in modern cracking processes

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3
Q

LIQUID ACIDS VS SOLID ACIDS

A

CATALYTIC CRACKING IN PETROLEUM REFINING
Liquid acids
Liquid acids are used such as HF in processes such as “hydrofluoric acid alkylation” to produce high-octane gasoline.
Solid acids
Zeolites, such as zeolite y, offer enhanced selectivity and stability in breaking down large hydrocarbons into gasoline

ESTERIFICATION AND TRANSESTERIFICATION IN BIODIESEL PRODUCTION
Liquid acids
Esterification uses sulfuric acid to convert FFAs
Solid acids
Replaced by sulfonated resins or solid superacid SO4/ZrO2 and convert free fatty acids to biodiesel with heightened sensitivity

ISOMERIZATION AND ALKYLATION REACTIONS
Liquid acids
HCl or liquid-phase solid acid catalysts are employed to form branched isomer
Solid acids
Zeolite beta provided better control over reaction conditions, increased selectivity, and improved safety.

DEHYDRATION REACTIONS
Liquid acids
Sulfuric acid (H2SO4) and phosphoric acid (H3PO4), are commonly used in dehydration reactions
Solid acids
Silica-alumina offered advantages in terms of stability, reusability, and ease of handling

ENVIRONMENTAL MONITORING
Liquid acids
Were used in analytical methods for environmental monitoring, but they might involve hazardous reagents
Solid acids
Have found applications in sensor technologies for pollutant detection, providing a safer and more selective approach.

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4
Q

Environmental Monitoring

A

encompasses the systematic collection of data to understand the health of our natural surroundings and to ensure compliance with environmental regulations

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5
Q

Objectives of Environmental Monitoring

A

Assessing Water and Air Quality
Identifying And Quantifying Pollutants
Understanding Chemical Transformations

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6
Q

TYPES OF SACs USED in Environmental Monitoring

A

Zeolites
adept at selectively adsorbing pollutants in water, capturing gases in air quality assessments, and aiding soil remediation efforts

Metal Oxides
acting as sensitive materials for gas sensors that detect and quantify pollutants, contributing to air quality assessments

Heteropolyacids
contribute to the degradation of pollutants in water and air, showcasing promise in sustainable environmental remediation

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7
Q

SACs disadvantages

A

WASTE GENERATION
Ineffectiveness due to
poisoning or fouling leads
to the disposal of spent
catalysts, contributing to
solid waste generation.

CONTAMINATION POTENTIAL
Discarded catalysts
may contain harmful
compounds, posing
environmental risks if
not handled properly
and potentially causing
soil and water pollution.

MANUFACTURING PROCESSES
The manufacturing of
solid acid catalysts
may involve energy-
intensive processes,
contributing to air
pollution and
greenhouse gas
emissions

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8
Q

Advantages of SACs

A

Continuous Production
Temperature Flexibility
Easy Separation
Non-Corrosive
Minimized By-Product Formation
Multifunctional/Reusable

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9
Q

solid acid catalysis: BIOMASS

A

accelerates reactions,
optimizing the transformation
of renewable biomass into
valuable products like biofuels
and biochemicals by providing
a surface for enhanced
reaction rates and selective
pathways.

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10
Q

FUNCTION OF SOLID CATALYSIS IN BIOMASS CONVERSION

A

Enhancement of reaction rates
Selective catalysis
Improved yield and product quality
Stabilization of reaction intermediates
Applicability to diverse biomass feedstocks
Facilitation of chemical reactions
Catalytic upgrading
Reusability and longevity
Control of reaction conditions

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11
Q

APPLICATION OF S.A.C. ON PRODUCTION OF BIOMASS

A

Biomass dehydration:
Solid acid catalysts, like zeolites, convert biomass sugars to platform chemicals, such as hydroxymethylfurfural (hmf)

Biodiesel production:
Solid acid catalysts drive transesterification, converting triglycerides in biomass into biodiesel and glycerol.

Hydrolysis of biomass polymers:
Solid acid catalysts aid in biomass polymer hydrolysis, turning cellulose and hemicellulose into sugars for biofuels

Upgrading bio-oils:
In pyrolysis, solid acid catalysts enhance bio-oil quality by reducing acidity and improving stability

Esterification reactions:
Solid acid catalysts catalyze esterification, contributing to biodiesel and biofuel synthesis from biomass-derived feedstocks.

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12
Q

ZIRCONIA-BASED SOLID ACID CATALYSTS FOR BIOMASS CONVERSION

A

Zirconia and its derivatives are praised for their strong acidity, stability, versatility, high catalytic performance, easy recovery and reusability, making them practical and multifunctional in acid-catalyzed biomass conversions

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13
Q

BIOMASS: COMPARE AND CONTRAST

A

With solid acid catalyst
-improved efficiency
-higher selectivity
-diverse product range
-cost effective solutions
-milder reaction conditions

Without solid acid catalyst
-traditional processes
-established practices
-potentially harsher conditions

Both
-sustainable energy
-biomass utilization

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14
Q

APPLICATION OF S.A.C ON FDC

A

FLAVOR ENHANCERS AND FOOD ADDITIVES:
Enhance food products by catalyzing processes like esterification and acetylation, creating flavor enhancers and additives that improve taste, aroma, and overall sensory experience.

HYDROLYSIS OF STARCH
Solid acid catalysts can be employed in the hydrolysis of starch to produce glucose. This glucose can be further processed into sweeteners, and other food additives.

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15
Q

APPLICATION OF S.A.C ON THE DRUG INDUSTRY

A

ESTERIFICATION AND TRANSESTERIFICATION REACTIONS:
These reactions are fundamental in the production of drug intermediates and final pharmaceutical products.

ACID-CATALYZED REACTIONS:
Some drug synthesis processes involve acid-catalyzed steps. Solid acid catalysts provide an alternative to liquid acids, offering easier separation and reduced environmental Impact.

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16
Q

APPLICATION OF S.A.C. ON THE COSMETIC INDUSTRY

A

ESTERIFICATION FOR COSMETIC INGREDIENTS:
Solid acid catalysts are employed in the esterification reactions necessary for the synthesis of cosmetic ingredients, including esters used in perfumes, lotions, and other beauty products.

FATTY ACID MODIFICATION:
Solid acid catalysis can be applied in modifying fatty acids to create new cosmetic ingredients with specific properties, enhancing the performance of cosmetic formulations.

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17
Q

APPLICATION OF S.A.C. ON POWER AND TECHNOLOGY

A

play essential roles in various energy-related applications, aiding in cleaner energy generation, environmental protection, and the development of sustainable technologies. Their use contributes to improving efficiency, reducing environmental impacts, and advancing renewable energy initiatives

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18
Q

GENERAL CONSIDERATIONS AND CHALLENGES OF SAC

A

General Considerations:
Efficiency and Selectivity
Environmental Impact
Regulatory Compliance

Challenges:
Catalyst Stability
Catalyst Recovery
Toxicity and Safety

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19
Q

SYMBIOSIS OF SOLID ACID CATALYSIS AND GREEN TECHNOLOGIES

A

is pivotal in efficiently converting biomass into valuable biofuels and biochemicals. This dynamic partnership addresses the demand for alternative energy, minimizing environmental impact and ushering in a cleaner, greener future

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20
Q

What is Nanotechnology?

A

Nanotechnology is the general term for designing and making anything whose use depends on specific structure at the nanoscale.

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21
Q

Nanoproducts

A

Sunscreen
Clothing
Furniture
Adhesives
Coatings for car paintwork
Sports equipment
Computers
Food
Medicine
Fireproofing

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22
Q

Green nanotechnology

A

Green nanotechnology is a branch of green technology that utilizes the concepts of green chemistry and green engineering towards a sustainable design, manufacture, use, and end-of-life of nanomaterials.

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23
Q

Main Advantages of green nanotechnology

A

Increased energy efficiency
Reduced waste and greenhouse gas emission
Decreased consumption of non-renewable raw materials

24
Q

Branches of Green Nanotechnology

A

Energy
Cosmetics
Medicines and Drugs
NanoFabrication
Nanobiotechnology
BioEngineering
Optical Engineering

25
Q

Green nanomaterials

A

Green nanomaterials are considered safe, eco-friendly materials and are currently used in various industries.

26
Q

Phytoformulations in Medicine

A

In phytoformulation research, developing nanotechnology-based dosage forms has a great number of advantages for herbal drugs.
These include enhancement of solubility and bioavailability, improvement of stability, suppression of toxicity, sustained delivery, and defense against physical and chemical degradation.
Therefore, problems associated with plant medicines can be overcome with nano-sized drug delivery systems (NDDS) of herbal drugs, having a potential future for enhancing their activity.

27
Q

Plant-derived nanostructures and applications

A

Proteins-based NPs:
Controlled drug & gene delivery
Bioactive compound delivery
Tissue engineering
Food industry

Polysaccharides-based NPs:
Drug delivery systems based on nanocellulose
Drug excipients
Blood vessel replacement

Carbon-based nanostructures:
Bioimaging
Biosensor
Optoelectronic
Photocatalyst
Electrodes in energy storage devices
Organic photovoltaic cells

Exosome-like NPs:
Oral delivery
Modulation of intestinal tissue renewal
processes

Adhesive NPs:
Tissue engineering & biomedical applications
Platelet aggregation, leading to clotting, & the sealing of wounds

Silica NPs:
Lithium-ion battery
Nanoelectronics
Energy harvesting
Energy storage

Lipids-based NPs:
Generation of soft nanomaterials such as nanotubes, nanofibers, gels and surfactants
Biomedical applications

28
Q

Nanoremediation

A

Nanoremediation is the implementation of
nanotechnology in the degradation and
transformation of toxic recalcitrant pollutants
for environmental clean-up.

29
Q

Nanoremediation of contaminated water, soil, and air is achieved by:

A

adsorbing the
pollutants onto the
surfaces of the
nanoscale objects,

catalysing reactions and
subsequently degrading the
pollutants through the
application of nanoscale
objects,

and nanoporous
membrane-mediated
filtration.

30
Q

Nanoremediation Applications

A

Dye degradation
Wastewater management
Nanoremediation of gaseous pollutants
Nanotechnology for remediation of crude oil
Nanoscale objects in heavy metal remediation

31
Q

NMs in the nanoremediation of Water

A

Metal and Metal-Based Nanomaterials
> Zero-Valent Metal Nanoparticles
> Metal Oxide Nanoparticles

Carbon-Based Nanomaterials
Different types of nanomaterials based on this compound have been widely employed, in the last decades, in wastewater treatment, specifically in the removal of dyes and heavy metals due to its non-toxicity, abundance, ease of preparation, high surface area and porosity, stability of structure, and high sorption capacity.

Polymer-Based Nanomaterials
Different alternatives based on polymer nanotechnology could be employed in water treatment, such as nanoparticles, nanocomposites, or nanofiltration membranes.

32
Q

Zero-Valent Metal Nanoparticles

A

Silver Nanoparticles
Silver nanoparticles are good antimicrobial agents

Iron Nanoparticles
Iron has excellent adsorption properties, can precipitate and oxidize, and is low cost

Zinc Nanoparticles
Zinc is a stronger reductant compared with iron.

33
Q

Metal Oxide Nanoparticles

A

TiO2 Nanoparticles
Titanium dioxide NPs are
exceptional photocatalysts
due to their high
photocatalytic activity,
reasonable price,
photostability, and chemical
and biological stability

Zn Nanoparticles
Zinc oxide NPs have
direct and wide band gap
in the near-UV spectral
region, strong oxidation
ability, and good
photocatalytic property

Iron Oxides Nanoparticles
In recent years, there is
a growing interest in
the use of iron oxides
nanoparticles for the
removal of heavy metal
due to their simplicity
and availability.

34
Q

Carbon-Based Nanomaterials

A

Nanoporous-activated carbon
Carbon-based adsorbents
present good adsorption
capacity in the removal of
contaminants present in
wastewater.

Carbon nanotubes
With an extremely large specific
surface area and abundant porous
structures, carbon nanotubes
possess exceptional adsorption
capabilities and high adsorption
efficiencies for numerous kinds of
contaminants.

Graphene
Due to its large specific surface
area, many functional groups,
and excellent charge carrier
mobility, graphene-based
materials are adsorbents for
wastewater decontamination.

Fullerenes
The low aggregation tendency and
large specific surface area of
fullerenes allow them to be used
as adsorbents to remove heavy
metals in industrial wastewater.

35
Q

Chitosan Nanoparticles: An Exemplary Green Nanomaterial

A

Chitosan is a bioremediable polysaccharide synthesized from chitin deacetylation. The most important factor for using chitosan lies in its properties like biodegradability, biocompatibility and economic feasibility which makes it more useful for bioremediation and biomedical applications. The good adsorbent properties help in removing the hazardous contaminations from wastewater. To improvise and enhance its stability as well as sensitivity, chitosan can be modified physically by changing it into different forms and chemically by crosslinking and grafting. Chitosan nanoparticles possess relatively larger surface area and higher adsorption potency.

36
Q

Chitosan-based nanomaterials uses

A
  • Removal of dyes
  • Removal of pesticides
  • Removal of other organic pollutants
37
Q

CATALYSTS: definition and advantages

A

Catalysts are substances that speed up chemical reactions without being consumed in the process.
They provide an alternative reaction pathway with a lower activation energy than the uncatalysed reaction.
The reaction can occur at lower temperatures or pressures, which can lead to significant energy savings.
They can be homogeneous or heterogeneous.

38
Q

IMPORTANCE OF CATALYST IN GREEN CHEMISTRY

A

EFFICIENCY
REDUCED WASTE
ENERGY SAVINGS
SAFETY
SUSTAINABILITY

39
Q

Heterogeneous catalysis

A

is a type of catalysis where the phase of the catalysts differs from that of the reactants or products.

This process contrasts with homogeneous catalysis where the reactants, products, and catalyst exist in the same phase.

catalyst typically in a solid phase, and the reactants are in a gas phase. The process involves a cycle of molecular adsorption, reaction, and desorption occurring at the catalyst surface.

40
Q

Absorption

A

is an essential step in heterogeneous catalysis. It is the process by which a gas (or solution) phase molecule (the adsorbate) binds to solid (or liquid) surface atoms (the adsorbent).
The reverse of adsorption is desorption, where the adsorbate splits from the adsorbent.

41
Q

2 TYPES OF ABSORPTION IN HETEROGENEOUS CATALYSIS

A

PHYSISORPTION
is weakly bound
adsorption, involves
weak Van der Waals
forces and is reversible

CHEMISORPTION
Is strongly bound
adsorption, involves
stronger chemical bonds
and is usually irreversible.

42
Q

HOW ARE HETEROGENEOUS CATALYSIS USED

A

CHEMICAL INDUSTRY
Haber-Bosch process for the synthesis of ammonia from nitrogen and hydrogen gases uses an iron catalyst.

OIL REFINING
Processes such as cracking, where large hydrocarbon molecules are broken down into smaller ones, use solid catalysts.

AUTOMOTIVE INDUSTRY
Catalytic converters are used in vehicles to reduce harmful emissions.

ENVIRONMENTAL APPLICATIONS
Selective Catalytic Reduction (SCR) is a process that uses a vanadium-based catalyst to convert nitrogen oxides, a harmful pollutant, into nitrogen and water.

ENERGY PRODUCTION
steam reforming of natural gas to produce hydrogen.

43
Q

WHY HETEROGENEOUS CATALYSIS

A

EASE OF SEPARATION
Since the catalyst is in a
different phase (usually solid)
than the reactants and products
(usually liquid or gas), it can be
easily separated out by simple
methods like filtration or
decantation.

REUSABILITY
the catalyst can be
recovered, regenerated if
necessary, and then used
again for subsequent
reactions.

STABILITY
they are often resistant
to decomposition under
the reaction conditions

HIGH SURFACE AREA
this allows for a large number
of active sites where the
reaction can take place

CONTROL OVER SELECTIVITY
the size and shape of the pores in
a porous catalyst can influence
which reactants are able to
access the active sites, thereby
influencing the products that are
formed

COST-EFFECTIVENESS
The ability to easily
separate and reuse the
catalyst can significantly
reduce the overall cost of
the process

44
Q

TRANSITION METALS

A

Transition metals are chemical elements that have valence electrons in two shells instead of only one.
They are placed in the block in the middle of the Periodic Table, between Groups 2 and 3.
Transition metals form ions with different charges
The elements are called “transition” metals because the English chemistry Charles Bury used the term in 1921 to describe the transition series of elements

45
Q

WHY TRANSITION METAL AS CATALYST

A

Ability to alter oxidation state
Adsorb and activate other substances on their surface
Often form vibrantly colored complexes
Employed as catalysts in elemental form or in compounds
Selective, active, and stable

46
Q

SUPRAMOLECULAR SOLID CATALYST

A

class of catalysts that are formed by the self-assembly of molecular components into a larger structure
These catalysts are unique because they can be designed and synthesized to have specific properties, such as selectivity for a particular reaction or stability under certain conditions.
The term “supramolecular” refers to the fact that these catalysts are made up of multiple molecules that are assembled together through non-covalent interactions, such as hydrogen bonding, van der Waals forces, and π-π interactions.

47
Q

SUPRAMOLECULAR SOLID CATALYST ADVANTAGES

A

RECYCLABILITY
Because they are solid, they can be easily separated from the reaction mixture and reused, reducing waste and improving efficiency

VERSATILITY
By changing the molecular components used in the assembly, it’s possible to create a wide variety of catalysts with different properties, making them suitable for a wide range of applications.

48
Q

ORGANIC–INORGANIC SUPRAMOLECULAR SOLID CATALYST

A

They are essentially coordination polymers and metal-organic frameworks that serve as synthetic hosts for mediating chemical reactions highly versatile

49
Q

COORDINATION POLYMERS

A

These highly crystalline materials are constructed from assembling of to form one-, two-, and three-dimensional structures.
One important classification of coordination polymers is referred to as dimensionality.
Coordination polymers can also be used to space metal atoms out evenly within a structure that has a lot of surface area, which could promote catalytic efficiency.

50
Q

METAL-ORGANIC FRAMEWORKS

A

are a class of compounds consisting of metal ions or clusters, also known as secondary building units (SBUs), coordinated to organic ligands to form one-, two-, or three-dimensional structures.
The organic ligands included are sometimes referred to as “struts” or “linkers”

51
Q

Supramolecular Catalysts subsets

A

Supramolecular Catalysts > Organic-inorganic > Coordination polymers > Metal-organic framework

52
Q

CLASSIFICATION OF DEFECT STRUCTURE IN METAL‒ORGANIC FRAMEWORKS

A

Perfect
Dislocated atoms or ions
Missing atoms or ions
Missing metal nodes
Missing organic linkers
Mssing points or cluster:
> Local defects
> Large-scale defects

53
Q

APPLICATION OF CATALYST

A

KNOEVENAGEL CONDENSATION
a nucleophilic addition of an active hydrogen compound to a carbonyl group followed by a dehydration reaction in which a molecule of water is eliminated (hence condensation)

54
Q

BIOCATALYSIS AND ENZYME CATALYZED REACTIONS

A

Refers to the use of living (biological)
systems or their parts to speed up
(catalyze) chemical reactions. In
biocatalytic processes, natural catalysts,
such as enzymes, perform chemical
transformations on organic compounds

Enzyme-catalyzed reactions occur in
two steps. Initially, an enzyme and
substrate form an intermediate
compound called the enzyme-substrate
complex. This complex can revert to the
original substrate and enzyme. Once
formed, the complex allows the enzyme
to catalyze the formation of the product,
which is then released.

The enzyme and substrate are held
together in the complex by hydrogen
bonding and other electrostatic
interactions. The active site, a pocket
on the enzyme surface where the
substrate is transformed into the
product, has a unique conformation
complementary to the substrate
structure, akin to a key fitting into a
lock.

55
Q

WHY ENZYMES SHOULD BE IMMOBILIZED

A

Enzymes necessitate immobilization on a solid support for easy separation and recovery
also to enhance enzyme activity
however the immobilization method must maintain maximum enzyme activity without obstructing the diffusion of analytes to and from the enzyme active site

56
Q

METAL-ORGANIC FRAMEWORKS AS SOLID SUPPORT

A

MOFs have intriguing physico-chemical
properties, such as large and adjustable pore
size, pore shape, pore volume, and
polar/apolar balance. These properties make
MOFs ideal for creating a stabilizing
microenvironment for enzymes through
specific host-guest interactions and/or
confinement effect, similar to what has been
observed with other organic molecules.

57
Q

STRATEGIES FOR ENZYME IMMOBILIZATION WITH MOFS

A

surface adsorption
covalent binding
cage inclusion
in-situ MOF synthesis

CHM181 (7 decks)

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