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Catalytic Cracking Process Overview
45 Questions
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Catalytic Cracking Process Overview

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@SmittenGradient

Questions and Answers

What is the primary purpose of the catalyst stripper in the catalytic cracking process?

  • To burn coke at high temperature
  • To preheat the feed
  • To separate products from catalyst particles (correct)
  • To distill lighter fractions

    • The temperature required for catalytic cracking is below 500 °C.

    False

    What is the typical temperature range for burning coke in the regenerator?

    680°C - 720°C

    The feed sent to the riser is typically composed of _____ distillation gas oil.

    <p>atmospheric</p> Signup and view all the answers

    Match the following components with their functions in catalytic cracking:

    <p>Riser = Where catalytic cracking occurs Regenerator = Burns coke to regenerate catalyst Fractionator = Separates lighter fractions Cyclones = Assists in product separation from catalysts</p> Signup and view all the answers

    What is the role of the catalyst particles in the catalytic cracking process?

    <p>To provide heat for the reaction</p> Signup and view all the answers

    The introduction of millisecond catalytic cracking (MSCC) minimizes non-selective post riser cracking.

    <p>True</p> Signup and view all the answers

    How long does catalytic cracking typically take in the riser?

    <p>2-4 seconds</p> Signup and view all the answers

    The products from catalytic cracking are sent to the _____ for separation.

    <p>fractionator</p> Signup and view all the answers

    What is the common feed rate for the riser in the catalytic cracking process?

    <p>200 t per hour</p> Signup and view all the answers

    What is the primary reason for performing vapor stripping in catalytic cracking?

    <p>To remove a significant part of the poisoning tar</p> Signup and view all the answers

    Catalytic cracking processes utilize raw materials that come only from distillation under vacuum.

    <p>False</p> Signup and view all the answers

    What type of catalysts are used in the catalytic cracking process to achieve high yields?

    <p>Amorphous silica-alumina and crystalline zeolite</p> Signup and view all the answers

    The process of catalytic cracking can lead to the production of __________ molecules with high value.

    <p>branched alkanes, branched alkenes, cycloalkenes, and aromatic</p> Signup and view all the answers

    Match the following catalysts with their characteristics:

    <p>Amorphous silica-alumina = 70% yield Crystalline zeolite = 85% yield Synthetic amorphous aluminum-silicates = Good reactivity and high gasoline selectivity Bronsted acid = Extracts the hydride ion from paraffin</p> Signup and view all the answers

    Which of the following is a step that follows the recovery and separation of products in catalytic cracking?

    <p>Vapor stripping</p> Signup and view all the answers

    The cationic mechanism involves the addition of a catalyst to a double bond, resulting in unsaturated hydrocarbons.

    <p>True</p> Signup and view all the answers

    What happens during the propagation step of the cationic mechanism?

    <p>The positive charge is transferred from a primary to a more stable tertiary position.</p> Signup and view all the answers

    Catalysts used in catalytic cracking like zeolites have a yield of __________ part of the initial feedstock.

    <p>85%</p> Signup and view all the answers

    What process can remove sulfur compounds during hydrotreating?

    <p>All of the above</p> Signup and view all the answers

    Nitrogen species can generate sulfur during the catalyst regeneration process.

    <p>False</p> Signup and view all the answers

    Name the catalyst types commonly used in hydrotreating.

    <p>Co-Mo, Ni-Mo, Ni-W</p> Signup and view all the answers

    The removal of unwanted species in hydrotreating is performed at a pressure range of _____ atm.

    <p>5-20</p> Signup and view all the answers

    Match the following pollutants with their associated removal methods:

    <p>Sulfur = Amine washing Oxygen = Prevent Pt catalyst poisoning Nitrogen = Generate ammonia Heavy metals = Reduce catalyst activity</p> Signup and view all the answers

    Which of the following statements is NOT true regarding sulfur and catalyst activity?

    <p>Sulfur compounds pose no risk to catalysts.</p> Signup and view all the answers

    Hydrotreating can help in upgrading lube oil properties under mild conditions.

    <p>True</p> Signup and view all the answers

    What are the major effects of arsenic on the Pt catalyst?

    <p>Poisoning of the catalyst</p> Signup and view all the answers

    Organometallic compounds transform into _____ metals that can reduce catalyst activity.

    <p>heavy</p> Signup and view all the answers

    Match the type of hydrotreating with its purpose:

    <p>Mild hydrotreating = Upgrading lube oils High pressure hydrotreating = Removing sulfur compounds Hydrotreating = Preventing catalyst deactivation Desulfurization = Improving diesel fuels</p> Signup and view all the answers

    What is the primary target of the deasphalting process?

    <p>Increase gas oil yield</p> Signup and view all the answers

    The extraction and phase separation rates of supercritical fluids are lower than those of typical extraction processes.

    <p>False</p> Signup and view all the answers

    What is the extracted material called in the deasphalting process?

    <p>Deasphalted Oil (DAO)</p> Signup and view all the answers

    Hydrocarbon supercritical solvents, such as _____, are used in modern extraction processes.

    <p>CO2</p> Signup and view all the answers

    Match the following terms related to the deasphalting process:

    <p>DAO = Deasphalted Oil ROSE = Residuum Oil Supercritical Extraction MW = Molecular Weight psig = Pounds per square inch gauge</p> Signup and view all the answers

    What is the yield range for deasphalting processes?

    <p>75% to 80%</p> Signup and view all the answers

    Increasing the yield of the deasphalting process decreases the metal content in the extracted oil.

    <p>False</p> Signup and view all the answers

    What is a major benefit of the ROSE process?

    <p>Low investment costs and energy savings</p> Signup and view all the answers

    The original deasphalting process operated at _____ psig.

    <p>400</p> Signup and view all the answers

    What is the purpose of adding heat in the extraction stage of the deasphalting process?

    <p>To decrease solubility</p> Signup and view all the answers

    What is the primary benefit of co-feeding small amounts of water to the reactor?

    <p>It forms t-BuOH in situ</p> Signup and view all the answers

    Gasoline blending typically requires a mixture of 10–12 blendstocks.

    <p>False</p> Signup and view all the answers

    What are the primary physical properties monitored during product blending?

    <p>Density, volatility, and boiling range</p> Signup and view all the answers

    The _____ step involves separating isooctene from the unreacted feed.

    <p>purification</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Oligomerization = The process of forming larger molecules from smaller ones Hydrogenation = The chemical reaction of hydrogen with another compound Multi-component blending = Combining various blendstocks to produce a final product Gasoline = A mixture primarily used as a fuel for engines</p> Signup and view all the answers

    Which of the following is NOT a characteristic of refined products that is analyzed and monitored?

    <p>Color intensity</p> Signup and view all the answers

    Study Notes

    Catalytic Cracking Process

    • Catalytic cracking involves cracking, recovery and separation of products, and catalyst regeneration.
    • Raw materials include vacuum distillation products and bitumen residues without asphaltenes.
    • Major products are light diesel (low aromatics) and heavy diesel (high aromatics), utilized as fuel.

    Catalyst Poisoning and Regeneration

    • After cracking, catalysts can be poisoned by tar and carbon residues.
    • Vapor stripping and high-temperature air combustion remove poison from catalysts.
    • American refineries use amorphous silica-alumina (70% yield) and crystalline zeolite (85% yield) catalysts.

    Carbocationic Mechanism

    • Catalytic reactions employ a carbocationic mechanism due to acidic catalysts.
    • Unsaturated hydrocarbons react via Markovnikov addition, while paraffins lose hydride ions to form conjugated bases.

    Catalyst Types and Performance

    • Synthetic amorphous aluminosilicates were the first catalysts used for good reactivity and high conversion rates.
    • Catalyst regeneration requires high temperatures to burn coke buildup without needing a furnace.

    Riser and Reaction Conditions

    • Preheated feed enters a riser (60m long, 1-2m diameter), where catalytic cracking happens within 2-4 seconds.
    • Reaction temperatures exceed 500°C, obtained by heating coke and contact with hot catalyst particles.

    Catalyst Stripper and Product Separation

    • A catalyst stripper utilizes steam to remove products from catalyst particles, assisted by cyclones.
    • Products are sent to a fractionator for distillation, separating lighter fractions from heavier oil.

    Innovations in Catalytic Cracking

    • Millisecond catalytic cracking (MSCC) improves gasoline selectivity by minimizing non-selective reactions.
    • Contaminants like sulfur, nitrogen, oxygen, and arsenic can poison catalysts, necessitating removal processes.

    Hydrotreating Process

    • Hydrotreating removes sulfur and other compounds, preventing catalyst poisoning.
    • Employs catalysts like Co-Mo, Ni-Mo, or Ni-W at pressures of 5-20 atm.

    Deasphalting Techniques

    • Deasphalting separates hydrocarbons based on different solubilities; yields between 75%-80%.
    • Residuum Oil Supercritical Extraction (ROSE) uses supercritical solvents and offers high yield with lower energy costs.

    Process Optimization

    • Higher temperatures (up to 900°C) and short reaction times increase desired product yields.
    • Various parameters must be optimized for effective hydrocarbon conversion and product yield.

    Gasoline Blending

    • Product blending requires combining multiple streams to meet standards for refined products.
    • Finished products are monitored for physical, chemical properties, and performance characteristics, ensuring compliance with industry regulations.

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    Description

    Explore the intricate process of catalytic cracking, which involves cracking, product recovery, and catalyst regeneration. Learn about the raw materials used, such as vacuum distillation and bitumen residues, and discover the products generated, including light and heavy diesel fuels. This quiz covers the essential concepts and applications in refining.

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