Tomcat como servidor web

Esse plugin é para vc rodar o tomcat pelo maven mesmo.. O erro que vc reportou, pelo menos eu acho, tem a ver com o estilo de criação do projeto... Na tag packaging do pom.xml, vc colocou o war?

<packaging>war</packaging>

Sim, consta essa anotação Segue como eu tentei fazer deixei o Jetty comentado, eu fiquei duvida se tenho que colocar a tag como o site do tomcat diz ou se coloco direto a tag . Obrigatoriamente preciso definir a variável catalina_home?

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>br.com.teste</groupId>
    <artifactId>maven</artifactId>
    <version>1.0</version>
    <packaging>war</packaging>

    <name>JSF - PrimeFaces com Maven</name>
    <repositories>
        <repository>
            <id>prime-repo</id>
            <name>Prime Repo</name>
            <url>http://repository.primefaces.org</url>
        </repository>
    </repositories>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

        <maven-compiler-plugin.version>3.5.1</maven-compiler-plugin.version>
        <jetty-maven-plugin.version>9.4.0.M0</jetty-maven-plugin.version>
    </properties>

    <dependencies>
        <!-- Servlet -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <!-- JSF -->
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>2.2.13</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>2.2.13</version>
            <scope>compile</scope>
        </dependency>
        <!-- PrimeFaces -->
        <dependency>
            <groupId>org.primefaces</groupId>
            <artifactId>primefaces</artifactId>
            <version>6.0</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>delta</artifactId>
            <version>1.0.10</version>
        </dependency>
        <!-- Quartz -->
        <dependency>
            <groupId>org.quartz-scheduler</groupId>
            <artifactId>quartz</artifactId>
            <version>2.2.3</version>
        </dependency>
        <dependency>
            <groupId>org.quartz-scheduler</groupId>
            <artifactId>quartz-jobs</artifactId>
            <version>2.2.3</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.16</version>
        </dependency>
    </dependencies>
    <build>
    <pluginManagement>
      <plugins>
         <plugin>
          <groupId>org.apache.tomcat.maven</groupId>
          <artifactId>tomcat7-maven-plugin</artifactId>
          <version>2.2</version>
        </plugin>
      </plugins>
    </pluginManagement>

<!--         <plugins> -->
<!--             <plugin> -->
<!--                 <groupId>org.apache.maven.plugins</groupId> -->
<!--                 <artifactId>maven-compiler-plugin</artifactId> -->
<!--                 <version>${maven-compiler-plugin.version}</version> -->
<!--                 <configuration> -->
<!--                     <source>1.8</source> -->
<!--                     <target>1.8</target> -->
<!--                 </configuration> -->
<!--             </plugin> -->
<!--             <plugin> -->
<!--                 <groupId>org.eclipse.jetty</groupId> -->
<!--                 <artifactId>jetty-maven-plugin</artifactId> -->
<!--                 <version>${jetty-maven-plugin.version}</version> -->
<!--                 <configuration> -->
<!--                     <httpConnector> -->
<!--                         <port>9090</port> -->
<!--                     </httpConnector> -->
<!--                     <webApp> -->
<!--                         <contextPath>/codenotfound</contextPath> -->
<!--                     </webApp> -->
<!--                 </configuration> -->
<!--             </plugin> -->
<!--         </plugins> -->
    </build>
</project>

Tem que declarar o no pom.xml também. Agora assim, vc não precisa ficar subindo o tomcat pelo maven... Adiciona o projeto no eclipse, associa ele ao tomcat do seu eclipse e ta resolvido.